It’s going to be hit and miss kind of thing. It’s all depends on each individual. I haven’t seen my doing it over my reef life but I heard there are yellow tang that eats corals. So you never know till you try
Multiple? You might strike luck, but hard to say... you could have all out war as well.
I have a CB and an Eibli (Red Stripe) in my 90 gallon, different species but both pygmies. It was a rough first few days, but now get along great.
Plenty of rockwork to establish hiding space would help imo.