They are great fish, feed them worms and they will be nice and fat and leave most of the fish in your tank alone. The suggestion on the clear tube is a winner, that way you can see it more often.
BGKs are relatively hardy and slow growing. You can house them with your stock without a problem. They aren't too sensitive to water changes, but make sure it's not going to cause a huge temperature change.
Alright, please, please, never use all caps again. There are, of course, situations where it is acceptable to do so, but you clearly are not in any.
I imagine the only thing you would have to do differently to get a ghost knife would be to feed it bloodworms at night. They are hardy and peaceful around other nonelectric fish that are too big to be eaten.