5 amps is probably the best setting to charge nickle metal batteries. You get good runtime and volts from that setting.
I think a rookie would do better with a car that understeers. That way they won't be spinning out on the track.
I don't think a rookie will notice a big difference of a 1.16 pack vs a 1.17. The will be too busy trying to drive the car to notice.
I also think a rookie should start off with the stock setup and just worry about learning to drive without wrecking. Once they get the basics of driving then worry about setting the car up to go faster.
My 2 cents.
