Congrats!

You really don't have to feed them at all. I think you will be pleasantly surprised (or horrified) that there are probably a few insects already in your house and some will probably find there way to your cape sundews.

Of course you can, but you really don't have to feed them all that much. Probably any of these would be fine, I would probably pick the crickets myself because they are cooler looking than a worm or snail.

Cape sundews are strong enough to capture flies & small crickets. But the big crickets pet store normally sell are too big & strong for Cape sundews.

I would advice to just let them do the feeding by themselves. There good at it.

I know that my plants can attract their own prey, but I would enjoy feeding them to see how they would react. And the crickets sold at Petsmart are mini-sized and dead.

P.S. When feeding the sundews, about how often should I feed them and how many insects?

Don't feed any of those mentioned. If anything, you can supplement them with typical fishfood, like bloodworms.