Never put buns with guinea pigs as already said.

The buns will need to be neutered once they are old enough/big enough. Female rabbits especially can be aggressive they suffer from their hormones, also females buns are at high risk of uterine cancer if left un-neutered. You need to spend time just sitting with them and getting them used to you on their terms. Bunnies generally dont like being picked up, they will get used to it but you need to hold them firmly supporting their bottom so they feel secure.