You can mix shrimp, but most people don't do it. With the types of shrimp you want to add, you will eventually end up with just the cherrys. Ghost and Amano shrimp need special conditions for their young to survive. You would have to replace them when they die. I'm not quiet sure what you mean by blue shrimp. The only blue shrimp I have seen are the ones on aquabid. I'm pretty sure these are mutations of cherry shrimp, similar to albino fish. If kept with cherrys they will most likely breed with them. The blue shrimps genes are recessive so if one mates with a cherry, you will only get red offspring. If two blue mate you will get blue offspring. I'm pretty sure it is the same with the yellow and orange shrimp as well.
I suggest that you go for only cherries. They can be expensive, but they breed like rabbits. So they are well worth the extra money and you can easily sell them.
