AWhat size tin tie bag do I need for 12 cake pops (without the stick)?

What's a tin tie bag?

Are you talking about those coffee-type bags that close with a twistie tie? This kind: http://www.specialtypak.com/files/2011/03/paper_tin_tie.jpg

If that's so, then how big are your cake balls? The only similar product I can think of is the the one that those uber yummy Lindt Chocolate Truffles come in. Mmm, I can't get enough of those round chocolate truffle balls.... But you could look at the size of that bag and see how many balls come in it. I'd be afraid they'd stick to each other without being individually wrapped though.

AThey will be dipped in choc. They shouldn't stick if the choc is hardened right?

Depends on where you live, if they'll be outside, etc. But maybe someone who does these regularly can chime in.