Justin getting back into flying from a good 10 years ago. I have a bunch of old 4.8 volt batt. I would love to replace them with new lipo but not sure what to pick. I would like get around 1300mah for my radio equ. in the plane. running 4 channels with 5 standard serveos. The new lipos i was lookinf at are all 7.4 volts or higher. Can i plug that right into my recever or is the voltage being higher going to be a problem? and if so what do i do to reduce the voltage. Also what does the c ratting mean like 20 c, or 30c, and how do i know what to choose.

Thanks for any help.
Justin