Well a little about what you might want to know in the hotels it is not customary to find wash cloths, there are hand towels and large bath towels. English is taught in school so everyone speaks English well. Credit card are widely accepted in stores, restaurants, hotels and supermarkets some places also accept American dollars. You are able to view the Northern Lights around the country but the best spots to get a better view is in areas where lights are limited and tours are available through different vendors that will take you half an hour to an hour out of Reykjavík. There are also tours via boats.
There are a lot of museums which are great to visit such as Aurora Reykjavík where you get a great lesson on how the Northern Lights (Aurora Borealis) and see an extensive video of lights from Iceland and other countries. There is the National Museum where you get a picture of Iceland from the Viking years to present (lifestyle, religion etc.) A popular site to visit is the prominent landmark, Perlan Wonders of Iceland. This building houses a planetarium, an ice cave replica and several other exhibits of some of the natural volcanic activity with some interactive demonstrations that gives you a real good idea of how the activity feels
From this building on the hill there is an opportunity for a panoramic view of Reykjavík from the observation deck.