I'm getting some Cresteds on the fourth, and I have a few questions. First off, if I use the Repashy food, do I need to dust the lobster roaches I'll soon get? Also, if two different color varieties breed, are the results usually favorable? Finally, is a 20-gallon long, which is much easier to use for various reasons, good for 3 of them? If not, I'll go with a 30 long. Thanks for the help.