Your AFB will more than likely jump out from lack of space, and trust me, they WILL find a way to. IMO, something like a 40 would be ideal.
I had 3 in my 110 together, and they did fine. They did eventually all die off within 2 years, as did all the other fish from that specific vendor.. but I loved them. I hand fed them krill!
As for what could go in the 10 gallon? Cardinal Tetras are very colorful, and $1 at petsmart right now. Neon tetras, guppies... Anything tetra or barb almost.