The shrimp will work fine in the 5 gallon. If you can find them, amano shimp are great too. Cherry shrimp are also a great shrimp to keep. Unless of course you're just keeping the ghost shrimp as food for the angels.
I personally wouldn't keep 3 angels in a 10g, I wouldn't even keep one. As lotus said they can get up to 10 inches. A 10g is 20 x12. It would be like expecting your cat to live in it's cat carrier all the time. They also enjoy a tank with a bit of height to it.