When I'm making a pumpkin pie, does it matter what sort of pumpkin I use? Are the specific varieties that are more suited to pies or can I just use any pumpkin?
You may use all sorts of pumpkins and squashes (a Cucurbita moschata or Cucurbita pepo may be called either, depending on variety) to make a pie. The Halloween types may not be the best choice: they tend to be stringy, not very sweet, and sometimes over treated with pesticides. Instead look for the small varieties (around 5 lbs.) called Sugar, Long Pie, or Trickster.
When making the pumpkin purée for a pie from scratch it is important to deal with the water content of the pumpkin. After you bake, cool, and purée the pumpkin, you may need to use a cheesecloth to wring the purée.
The advice is to stay clear of the ones specifically tuned for halloween. To a first approximation, if you find it in the grocery, it's good.