I don't know about the tank idea, I've tried something similar with leopard gecko eggs years ago but they ended up going bad... it could definitely work though lol (even though it honestly sounds like too much work...)
Usually white eggs are good.
Does one of the cresties have a good sized "bulge" under its tail? That'd be the boy

Since you only have 2 adults, I'd assume you have multiple clutches worth of eggs which means you should candle them lol. It's actually really really easy to do, just take a flashlight (pen lights work really well) and hold it under the egg in a dark room. Be very careful to not rotate or tip the egg from its original position. What you see will vary a lot depending on how old the egg is (assuming its not a dud)
Within a few days you see a red vein that makes a complete circle around the top of the egg. It grows and grows til eventually you can barely make out a little gecko inside (just before hatching you see nothing but shadow because they block the light lol)
It's actually really cool looking once you can make out the babies. Last year I had one move while I was candling it! (it startled me...) It hatched probably about a week later.
It should take between 2 and 3 months to hatch. Mine last year all took about 70 days to hatch.
As far as when to rehome them, that kinda depends on the experience of who they go to and your personal preference. I'd probably wait a month or so, or at least wait til they're eating and pooing properly. Hatchlings pretty much have the same needs as the adults except spray a little more often for aiding with sheds and drinking. (be careful with water bowls, if you have one make sure its shallow and put maybe some soft stones or a plastic plant in it so they can climb out. The hatchlings can drown in it (and trust me, that's way too sad to deal with) :'(
*just in case it doesn't go "unsaid" they can't be housed with adults or they could become a snack...:-(