Mine weened off feeders onto raw shrimp pretty easy. I stuff algea wafers in the shimp, and just the other night one of them started eating the algea wafers I threw in for the pleco that's in with them.
Had them for 2 years now and two are around 16 inches, the other seems to be holding around 10". they were around 4-5" when I got them. I've read different places that they can get over 20".....we'll see