Congratulations on all the good things happening in your life at the moment

2. I believe it was Sunken Temple, with the boss who spawned unlimited skeletons has been nerfed. You no longer recieve exp for the skeleton kills, correct? (bummer).
Correct. in the broader sense, Multiboxing is as good as it ever was and just as much fun. Actually having a tank makes all the difference in Northrend instances, although as you can see from other posts here, many are possible without.

If you don't manage to keep up with what's going on through regularly reading this site, I'd actually hold off on trying to get all up-to-speed with the changes until you've got the rig and connection sorted and you're right on the edge of launching into it.

You will have no problem getting a decent internet connection in Berlin. In Frankfurt, I have a 20Mb (yes, twenty) connection using Unity Media and haven't had a single problem with them in over 3 years of subscribing (*touches wood*). I've no idea if they serve Berlin, but your girlfriend will be able to find out for you.

She should also be able to find you a good source of cheaper hardware components.

Be really careful if you're planning to build your PC in the USA and then ship it over.

Unless you can get a Transfer of Residence exception (which you won't unless you have a permanent residency visa for Germany) you could well be hit with import duties that will outweigh the benefits of having gotten the components cheaper in the first place!!

I've bought quite a few components from amazon.de. They seem to use *alot* of "marketplace" type vendors on there, so you end up making direct contact with some sources worth keeping hold of, most of whom speak English.

By the time you've been round that loop a couple of times, you might well find that you're not that much worse off than buying in the US (depending on your negotiating skills).

edit:
You'll also have no problem finding English language editions of Windows and US layout keyboards over here.