Actually, it's a two-parter:
1) Can this battery be charged on an battery charger or must it be done in the unit or cradle?
2) Can I replace it with any battery I choose? I've got a Powerex 2000mAh NiMH that would be amazingly long lasting in this unit - provided that I don't have to worry about damaging it somehow by using something other than what was specified for it!