Any chance of creating breeding programs to make meaner monsters?
Yes. If one isn't in, I'll put
Sure its already been asked but, harem situations possible?
Likely no. I doubt the ESRB would smile on polygamous factions... and the breeding system will likely be rather... erm.... abstracted in any case.
Possible to marry things that are not memeber of faction, aka spirits or demons or outsiders or whatever?
Perhaps. I don't see why not, but I do see why, so there's a good chance.