"that big tube-y thing sticking out...it's not always there. it shrinks back into the shell and I have no idea what that is, either."
That's a siphon used to get oxygen out of the air. I don't think trapdoor snails have those. Apple snails certainly do. You may have a baby apple snail. If that's what it is, it's too young to lay eggs as of yet, and they'd be out of the water. See applesnail.net for all you need to know about apple snails.
"I'm beginning to think they aren't baby snails because they swim, but I'm gonna see what happens. Here's a little sketch i did of their shapes. There are 2 different shapes of "babies" and they're clear."
They're not baby snails which suck on the sides and are miniature versions of their parents. You may have cyclops, daphnia, or other microorganisms in the water. They are probably harmless. A drawing of a cyclops found of this site looks a lot like your one drawing:
http://www.iwight.com/branstone_farm/nature.aspThis site has actual photos of one and some other tiny animals:
http://members.aol.com/moresciencestuff/microlife.html"I have seen little gelly globs hanging off the leaves with small brown dots in them, but I think it just might be algae. "
If your snail is an apple snail as I suspect, then it would not lay eggs under water so unless you have other snails in there, those globs aren't snail eggs.