I never really thought I'd like cories until I got a few. They're hilarious to watch and if you're looking for something to be a complimentary background fish to a flashy Betta, they do the trick. I did find that the Panda cories are more sensitive than other types, but that may just be because they're so much smaller. If you're willing to keep an eye on water prams, especially pH, they are a pretty neat little fish. Cories in general are pretty sensitive, but as long as your tank is already cycled and planted and they've got lots of hiding places, they should do well. I have no idea about how well they'd do with that many shrimp. I've just got 3 cories, the betta, and 2 ghost shrimp in my 10 gallon and I've never had any problems with them competing with each other. Someone else might have an idea of how that many shrimp will interact with your fish. All I know is that in general, the more hiding places you have for tank mates in with your betta, the better and it looks like you've got that part covered.
Proud mom of Samuel, the red, white and blue VT and Darius, the purple and red HM.
Samuel's Tank Mates:
4 peppered Cory Cats
1 Siamese Algae Eater