Too many at once 2 fish is about maximum imange if several people turned up to your house in the same day plus don't put tetras in with barbs (you don't want to learn that the hard way)
Rainbow sharks are awesome I have one buy them small so you can watch them grow i wouldn't keep 2 different species I had a coal blue and a dwarf together and they had a fight the coral blue died in the fight (I was on holidays) and the dwarf Reid of an infected wound it was to late to treat it...
So no to the shrimp thing what about crayfish flutter moth I only have 5 hiding spots one is taken up by my shark and the Cory the other to the bristlenose and my mum won't let me
I have kept the bristlenose for four years without any probs shark quite a recent addition the tank size is fine is just I can't keep 7 catfish in one tank