I keep gammarus shrimp with hastatus cories (a little smaller than Pandas) and the gammarus shrimp are thrieving. They are in this tank as a readily available food source for my plecos but they have a healthy colony going and neither the corys not the L46 and L174 plecos have been able to wipe them out. Your adult RCS will be fine. I keep adult RCS males with them as well and I have yet to see them eat one. But the planaria are thrieving in this tank as well. If you are hoping the corys will take care of the planaria, you might be disappointed. Maybe larger corys would work but then the shrimp could be in danger. I would cut down on the feeding.
I've heard loaches can and will slaughter shrimp. Your results will vary with Corys since they are peaceful but can fit babies in their mouth.
I dealt with my planaria by getting a feeding dish, cutting back on feeding and getting some CPDs since I have a taller tank and they would inhabit the middle. I also got a Nerite snail to cleanup leftover detritus and not reproduce.