If you're just starting out, ignore NiMh (nickle based) batteries. They are old, expensive, sub par tech batteries. You want LiPo (lithium).
These will do fine for you. It's a 2 cell (7.4v) LiPo battery that won't be too hard on your internals.
The 11.1 version of that battery will give you a faster rate of fire and quicker cycle time for semi auto, but it will wear our your internal parts faster.