If you are going to put in ghost shrimps, make sure you monitor their relationship (Betta and Shrimp) and sometimes it can get pretty nasty for the both of them. My friends Betta got murdered by this really aggressive Ghost Shrimp he bought, the ghost shrimp some how managed to literally snip off bits of his caudal fin, pectoral fin were missing and this tail.
So yea just be careful. I removed all my shrimps and put them into a seperate tank with only Ghost Shrimps.