Sweden is generally a friendly and safe society. It is not even likely that you will be subjected to harassment when taking pictures et.al., as the situation regrettable is in some other places these days.
Communicating with people is not a problem, just speak clearly and slowly, and you will do just fine. With the exception for maybe Finland and Holland, there is no other people with better skills in English, outside the countries where it is spoken as a main language.
The society as a whole is well organised and civilised, with a good infrastructure. No crowding, there is plenty of space for everyone. Sweden is about the size of France or Germany, with only a tenth of that population. Most development is concentrated to cities or regions in the lower third of the country. But don't hesitate going outside the beaten path, Sweden is a very tourist oriented nation. Where you least expect it there is something exciting to see and do.
Don't worry about the price level. Most journalists telling you about Sweden stay in the capital, where prices are admittedly high. Offhand I maintain it is barely half of that in the rest of the nation. Sweden even has an explicitly lower sales tax (v.a.t) on everything related to tourism. Something to contemplate for nations levying punishing landing or leaving taxes, or even special hotelroom taxes.
With the exceptions of some VERY touristic places, either Euro or Dollars cannot be used as currency. You need Swedish money, that is KRONOR (SEK). Compared with Euro, just divide the Swedish prices in about a tenth. No need to make it more complicated than that. I bet there is hardly any nation where credit cards are more videly used. Some stores, especially travel agencies do not even accept cash payments. The same goes with local buses in some cities. Taxi, parking meters, and ticket vending machines usually take plastic. The younger generation, under 20 or so, hardly use cash at all.
This is more like a curiosity, as the legal framework barely bans anything, including going naked in public. But where the law ends, moral standards pick up. Swedes like equality, so when e.g. visiting a beach, you are expected to undress in similar fashion - lest you sholdn't come across as a peeping tom. Topless is not illegal, but Swedish women are reluctant to show off (woe betide those liking what they see). When there is no laws to provoke, the struggle against them lose its meaning. When the temperature pass app. 25 C (80 F), many women walk barefoot in the summer, while men bare their chest - even downtown.
In wintertime some 95 % of Swedes dress completely in BLACK. Somewhere around the turn of the month April to May, the tide changes overnight. Light clothes in both colours and style are required, no matter what kind of weather there is. White and pastel hues are very much in evidence, until it changes again - more gradually this time - in early October or so.
Only women and children use rain boots in cities (as a man with pink rain boots, I am hard to miss). Preshool children are strikingly often dressed in pink for girls, and darker colours for boys - so much for Swedish equality. In southern Sweden knitted caps have long been considered silly, while even caps with ear flaps are common in the north. Something that may almost render a teenager to be accosted in the south. Shawls are OK round the year.
As a general rule of thumb, Swedes dress down for work, but up for leisure...
You may have heard of binge drinking in the Vodka-belt. Yes that's true, Swedes have a rather tense relation to alcohol. It's kind of all or nothing. Swedes also admire the allegedly abundant drinking around the mediterranean area. I have never been to Greece, but I suspect that the holiday visitors may have got it all wrong. I can hardly believe that it is the local fishermen that party and drink from dusk until dawn. It is more plausible that it is fellow Scandinavian or Brits they have seen...
Swedes also show an almost religious reverence towards winos. Someone who party on weekdays must be really cool. Swedes appear to have a (not so) secret dream of turning to fulltime drinkers, if they just could afford it. Crimes done under the influence is handled with a most striking lenience by courts. To even kill somebody in affection in the state of drunkenness, will give a significant reduction in the time spent in jail - if at all. Drunk driving is on the other hand not accepted, although propably more common than we would like to know.
I would suggest July, most of September or late March as generally the best seasons for a visit to Sweden. June usually offers a lot of rain, and also thunder in the southern hinterlands. August may also be a bit rainy, but quite warm. May is often sunny and warm along the west coast, but coldness and even snow is often what you will get in Stockholm or above. April is fairly dry, but can be rather chilly all over the nation. October is the start of the real rain season in the south, and lasts until mid december. By then it is already winter in the north. Januari through Februari is winter in all of Sweden, with the exception for maybe Scania alone. Februari is when the snow cover reaches its peak. It is possible to ski or skate almost anywhere, but maybe not in the coastal areas in the lower third of the nation.
Even if the weather is better in summertime, there might still be a case to be made for the transit tourist to avoid mid June to mid August. Though most things aimed at tourists are open, the bus services peter out. There is only one city that have a decent service year round; Göteborg. Otherwise even the capital takes a summer break. If it is a hot summer, it can be good to know that Swedish vehicles usually lack air conditioning. The major exception is Västmanland (U state), where all buses have it.
To start with there is a network of domestic airlines, advisable for the furthest destinations, which otherwise could require up to 20 hours or so by train. The airline hub is Stockhom, with the most frequent route being to Luleå (some dozen flights a day). For shorter distances train is preferable. The national railways do not have a monopoly, but is mostly prevalent. It is often possible to combine a ticket for different operators and modes of transport. Just ask for a "resplus" (travel plus) ticket. Note that many state operated rail services are not covered by Interrail cards. Privately operated long distance buses run between numerous destinations, with Swebus as the major operator. The hub in this case is Jönköping.
Each of the 21 states/ provinces have their own state transit company. These functions as umbrella organistations for all local in-state routes. Normally they have a common color scheme, and ticket system. In a few cases city buses are exempt from the ticket cooperation, and may also hold a separate livery. Most cities do have a flat fare for all local routes, but it also happens that e.g. a circum navigating highway or other feature functions as a kind of barrier for an outer fare zone.
The reason for the separation in city versus country routes is problably historical, because most cities had either private or community owned bus companies just a few decades back. The long distance equivalent was often run by the national railways, or local private companies. Usually on a fixed permit to operate certain lines and areas, that rarely changed much once it was instituted. In these days most workings in both cities and countryside are subject to tendering procedures at some uneven intervalles. Often 5-7 years is given at a time.
If you travel by car, be aware of the significant distances. Compare with the map of central Europe! There is but a few good highways, mostly between the mayor cities in the south. Road rage is increasing, but so far kept on a reasonable level. Malign ineups are rarely occuring. Speed limits are regrettable mostly theoretical, depending on an all to obvious lack of police recourses. Remember the sheere size of the nation, versus the thin population density.
Priority to the right is law in Sweden, but never used. In Norway it is on the contrary a cardinal sin to NOT yield to vehicles coming from the right. Another peculiarity in Sweden is that you flash the indicator RIGHT (!) when turning left in a roundabout. That is actually the official recommendation these days. It was the other way around when I got my drivers license in the age of dinosaurs. Then again, most people don't use their indicators at all anymore. When the police look the other way for too long, the general populace eventually get used to some bad habits.
Swedes love to bash the American car culture. To be frank, I believe that Swedes in general use transit even less. When it comes to cities under some 40 000 citizens, hardly anyone in the age above a driving license rides the buses. I presume it is politically impossible for the moment, but really, it does not make much sense to keep this service at all. A free taxi available for ride at will would likely be more cost efficient.
Remember that it isn't the price that make people go by car, and a taxi often needs to be booked. So i estimate that not many people are slated to chose this option anyway. They want to feel the inherent power percieved in the operation of the pedals and levers. Or they are just lazy, thinking they have to ride in an easychair from spot A to B. By the end of the day, may I recommend that you savour the private limousine service all these empty buses constitutes. As long as it lasts.