There really isn't any more room for fish in there, and a lot of those fish will eventually need bigger tanks. The clown loaches especially. If you 1. Got rid of the fish that will be getting huge or 2. Get another, bigger tank, then you could get cichlids... but as pica_nuttalli said, you technically have cichlids already!
angels get large, and dont normally like tankmates... or each other for that matter... if you're talking about your 30g tank, and you already have angels in there, there wont be room for any other fish.
yeah, i'd say that was full-grown i'm amazed you've not had aggression issues between them; a 30g isn't that big.
but between the pleco, the RTBS and the angels, you don't really have room for any additional territorial fish. any cichlid you get is going to directly compete for space with one or more of these fish. although there are some gentle cichlids that one can special-order, even then they'll spark a competitive reaction from your current fish.
as for the "elonquin rasboras", pm a mod to move that thread to Characins. if i recall, that's something of a specialty fish and as such, the people in Characins are more likely to know some answers for you.
well my grandpa had 6 full grown angels and 3 corys in a 30 gallon tank and they were fine but the two that i have are two from that bunch of 6 and they are a mated pair thats why they dont fight but the male is about 5 inches and female 4 inches but the rbs might be gone today as he is beating up on my betta and i am going to exchange my pleco with either some otos or a bristlenose pleco