If it's Ravioli put semolina flour down first then put ravs on top as to not stick. Freeze for 20 min tops or else the ravioli will burst in the water. After they are frozen store in a plastic bag. Don't leave the bag out after its done when your going to use it cause they will thaw and stick.

I generally make extra and freeze it.

If they're sticking like that, it could be that your dough is too wet. Definitely toss 'em in flour, and don't pile it up too high. (before you cook it, shake off the excess flour, and use a big pot / lots of boiling water to compensate for the extra flour.

I've done a couple different cheese fillings, a sausage filling and a mushroom filling. I don't usually use a recipe, I just mix in whatever I have that sounds good until I like the consistency. The mushroom was the most wet but they froze well. The more wet the filling the less time you should leave them uncooked I think.

Either freeze them or cook them quick. So far that's never failed me.

With nearly all pasta, you'll find you need more flour on the surface than you think you do. As long as the flour stays on the surface, and you don't keep kneading it into the actual dough, you pretty much can't put too much flour on pasta.