What method can I use to cook pumpkin seeds so that they turn out crunchy

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 rules are the same as keeping rice, beans, or lentils: keep them in a container that the insects can't chew through, and do not allow them access. This means glass, thick plastic (not a bag), or metal. I would do my best to dry off the seeds to prevent mold growth, beforehand. Even laying them on a paper towel for 15-20 minutes should help.

If you have problems with mold, try using something like a canning jar and use fine cloth in place of the lid. It should keep bugs out and allow moisture to escape.

Refrigeration will greatly extend the life of your seeds; if bugs do not have a chance to lay eggs on them, and the seeds are sufficiently dry to prevent mold, they should refrigerate for months.

Freezing is also good idea, as this will kill any bug larvae and prevent microbial spoilage; I'd try freezing a small batch of seeds first to make sure the moisture doesn't split them open.