RE: 6V Receiver Bat Charge
No, the standard Futaba receiver charger is only rated for the 4.8 V battery. You can charge forever and will not get a full charge. You can order an 6.0 V overnight charger from Towers Hobbies. I have one and it is only about $12.00. You can use it for Nicad or Nimh cells.
Good luck
IDM