I think you should have a massive castle with a massive wall around the kingdom. It should contain Blacksmiths, minecraft, maybe even bits of the industrial revolution, it should be made of cobblestone for a medival feel and should be based on a mountain to protect it from enemy invasion.

yeah, id say about 15-25 to make a nice sized town.

3-13

You should at least have 10 - 20 houses 1-2 Blacksmiths 2-4 shops For a small town that's my opinion

If you wanted to make a typical medieval town I would just google a picture of some of the towns from Bethesda's Oblivion, They were very rustic medieval style cities that were scaled down from full size. I think most of them have roughly 20 or so buildings in a walled community. While its not realistic to what they are suppose to represent, they do look rather nice and if you make it too big its hard to really enjoy looking at it. Like my town which has gotten too big that most people who come to look at it never see more then half of it.

Depends on what type of town, some towns would have 5 buildings, others would have 20, some would even have 60.