Q: Multiple devices, one apple id, many problems :)

If I create new apple id's for the kids, will they lose any of the apps they currently use?  My son is very concerned about losing his "worlds" on Minecraft! LOL

Also, can I use their email addresses for new apple id's?

Yes, they will. All purchased apps are permanently tied to the Apple ID that purchased them, so they each will have to re-purchase their respective apps. Your son will, indeed, lose his worlds on Minecraft.

You can use their current email addresses for their Apple IDs as far as I'm aware. That is what I and my wife use for ours.

No. iDevices are single user devices. You cannot have two users with two IDs using the same device. Either they use one Apple ID or you buy one their own device.

Yes, Family Sharing will do that now.

Family Sharing and Apple IDs for kids

Family Sharing

A Guide to Family Sharing - iCloud - Apple Developer

Sharing purchased content with Family Sharing

No, you won't be able to use their current email address for another Apple ID.