Numbers are hard, but it's probably best to think in terms of farmsteads and households rather than villages. You can get a sense of what these looked like from the reconstruction of Eiríksstaðir (the farm of Eric the Red). You might imagine wedging up to about a dozen people in there, maybe with a few subsidiary farms up and down the valley, and some huts up in the hills for the shepherds. Altogether, a community of maybe 40-50 people within a day's walk from each other. It's easy to imagine why Icelanders were so excited whenever they got to meet up at larger assemblies or things.

Your best bet is probably to read up a bit on the sagas if you want more background. Two of the best are Njal's Saga and Laxdæla Saga. There's clunky old editions that you can find for free online, but I'm a big fan of the Penguin editions, which are scholarly and readable. Penguin also has a great and hefty Sagas of the Icelanders, which includes not only the Laxardal Saga but also, most notably, Egil's Saga and the Vinland Sagas. All of these are pretty popular books, so you can often find Very Good used copies reasonably priced. And if at all possible, support your local bookstore!