You can keep a colony with desexed rabbits and does. It may not be as easy as just putting them together - sometimes t is, sometimes they'll fight no matter what you do - but there's nothing that say that a desexed doe would be worse off than any other does.
A desexed buck may have a higher risk of getting in trouble with an unfixed buck than a doe would.
You can keep a buck with the does, it usually works. But you never know.
A group of rabbits need a lot of space and hideouts to break up chases and fights. Different levels are good too. Read about rabbit colonies
I'm not good with genetics but I figure you'll get dwarfs with a single mane gene, that may shed their mane with the molting. If the lionhead has a double gene.
True dwarfs may also give birth to ''peanuts'' which usually die the first couple of days. But stillborn or early dying kits are not too uncommon I guess in any breed.
How old are your does? Have they had kits before?
And out of curiosity - why are you concidering to breed them? For what purpose?
Welcome to RT, btw