I have a 29 gallon and currently have mollies, neon tetras, and 2 guppies in it. 8 Mollies may be a bit too much for a 29 gallon though. Mollies can get up to 4 inches. I currently have 4 adults and around 5 babies in mine. They can be aggressive but tend to only fight among themselves. They can also be food hogs but this can be overcome by feeding larger size, floating food along with the flakes or other small food. I would say stick to one type of molly and get 4 of either variety. I would get one of the others you mentioned and up the school to at least 6. They like to be in bigger groups. It makes them less likely to fight with other fish. You could then do some type of bottom dweller like Khuli loach. The shrimp may or may not be eaten by the mollies. My original ones lived with ghost shrimp and blue pearl shrimp, same type of shrimp as cherry. The original mollies left the shrimp alone. Their offspring however developed a real liking to shrimp babies and cleaned the tank out. Provide plenty of hiding places for the shrimp that the fish cannot get into. There is a site called aquaadvisor that allows you to input your tank size, filter, and fish and it tells you if they will work.
