Regarding town buses in Reykjavik, buy a one, three or seven day pass - that is an incredibly cheap way to go anywhere, any time from end to end of the entire capital area as often as you like. You will not feel as cold in Iceland as in the UK because unlike the UK everywhere in Iceland is heated - you get up feeling warm, the bus stations and every single building is heated to 20 degrees or more, and the buses are all warm. I know lots of people all over Europe who refuse to visit the UK because it is cold, wet and dreary. The weather in Iceland, as in the UK, is unpredictable - it could be unpleasant but (unlike the UK) you can actually have a freak heatwave in mid winter. Temperatures can go past 20 degrees somewhere in Iceland in December. Take with you wet weather clothing that is also good in windy conditions, but (depending on the length of stay) just dodge the weather ifþwhen it is bad and move around by transport between indoor venues.