err, not sure on festivums, rams I think 2:1 ration not sure on it and angels I would stick with a mated pair and then get some tetras or a pleco or some sor of catfish or schooling fish. Maybe butterfly can tell you about the rams or you can google it.
I have had no experience with rams so I'm not the person to ask about that. Sorry. And the reason I said no lobster is because most tetras are all over the tank and could be easy food for the lobster.