what receiver battery do i use?

hey i am building a gas boat and i am really new to the rc equipment side of things i and getting this controller/receivers pack http://www.hobbyking.com/hobbyking/...nd_Receiver_w_Rechargable_Li_ion_Battery.html and 3 of these servos http://www.hobbyking.com/hobbyking/store/__16269__HK15138_Standard_Analog_Servo_38g_4_3kg_0_17s.html as you can see im doing it on the cheap but i have no idea what type of battery or voltage to use on this setup to power the receiver and servos what would you recommend from hobby king? and it won't be on the water for long periods of time either? and on the receiver there's the 123 ports for the servos, + - port for the battery pack, but what's the VVC port for? hope you can help Ben