Generally anything not too aggressive should be fine with balas as they are terribley skittish. I would not recommend them for a beginner however due to the fact they easily grow past 12" and 14" is not unheard of. On top of their giant adult size they are a shoaling fish and as such should be kept in groups.
If you do decide you want them then the bare minimum tank size would be 6x18x18, but due to their higher oxygen requirements and desire to swim around the tank fast from time to time I wouldn't feel happy with adults in anything less than a 6x2x2.
With regards to eating other fish, once fully grown they will probably start snacking on neons and any other fish that will fit in their mouth.
These are one of a number of fish I really wish lfs did not keep so many of, as I'm sure most of them don't go to 150 gallon tanks.
HIH
Andy