There is only really 3 types of tropheus importing at this time. Sp. black, moorii, and brichardi. At least this is how we were learnt to keep which together with what.
The dubosi and ikola was considered as sp. black last time I checked.
Given the chance, they will crossbreed. But if you keep a group of each type, chance of crossbreeding will be much lower. But if you just want keeping a large number of them together and don't care much about breeding, you can mix and match.