As everyone always says, it depends on what your Betta's personaility is like. Cody has a very friendly personality, so i decided to put 4 neons in there with him and so far there hasn't been any flaring, tail nipping or conflicts.
I only had him since yesterday but he was housed with the neons at the pet store and they were all getting along smoothly :P
As for shrimps, i don't really know as i have a snail in mine. Might try shrimps soon.
My 6.1 Gallon Tank
Purple Veil Tail (m)