I get this, haha. I am really photosensitive so summers tend to be rough. Some nice blackout curtains is the way to go. There are ones that you can essentially velcro directly to the window. It involves a bit of work putting them on and taking them off all the time, but it is the most effective. I admit I'm too lazy to do that so I have double sets of blackout curtains and it does the job most of the time.

My (German) roomie had the same general attitude towards winters here when he first moved, but after a year or two he's now firmly in the "I'm going to retire somewhere far south" camp. I'm curious how you'll hold up!

Finding friends here is... well it depends a bit on where you are and what you do, I suppose. We are really into clubs and unions here, so if you find some sort of activity you enjoy doing (board game clubs, choirs, dancing, pottery classes, what have you) I'm sure you can make plenty of friends. One has to kind of put oneself out there and be open to it, then I think most people reciprocate in kind. Swedes have a bit of a rep for being cold and distant, but I think it has to do with our general mentality of not wanting to stick out and take up too much space. It makes us seem more distant than we actually are.

My hometown had a weekly developer meetup that advertised on meetup.com. My roomie found plenty of furries in the area via BARQ. I found a local board game club via facebook, and there will generally be fliers and information available at the local library. If the town you're going to has a Folkhögskola I'd recommend checking that out as well. They usually have smaller courses and classes that can be a lot of fun, and a great opportunity to meet people at, and in addition to that they often host events.

Then of course there'll be a notice board at the university that'll likely have lots of current events listed. The world is your oyster! :)