Speaking Icelandic is pretty much optional. At least in Reykjavík, the percentage of people who speak English is pretty close to 100%. The only problem you run into is the non-human interactions. Web sites, automated phone systems, labels on items in the store, etc., will usually be in Icelandic only. That's proven to be not too much of a problem. Google translate isn't very good, but it's usually enough to get a basic understanding of a web page or a letter you get in the mail. In shops, you're of course looking at the items, so even if you don't understand the words, you can recognize chicken when you see it. And of course there are a lot of American brands as well, so you see Coke and Pringles and the like with English labels.
Apartment prices seem to have ticked back upwards slightly from the lowest levels. Prices depend quite a lot on where you want to live and the level of amenities you require. 140.000 to 150.000 ISK can get you a "luxury" one-bedroom apartment pretty near to downtown. Below about 100.000 to 110.000 ISK and it seems you start making fairly significant sacrifices. A studio should be a bit cheaper. All the places I was interested in were in the upper part of that range, but I wanted things like a washer/dryer in the apartment, etc. You can look at http://www.leiga.is/leit/default.aspx (in Icelandic, of course) to see some examples of what apartments for rent are going for. The postal code for downtown is 101, but 105 and 107 are pretty nearby as well.