Need help with my G3-build

[JoFreak]

Hi everyone!
I've been thinking about and been planning my G3-build for a long time but now it's time to get on with it.

So, my first question is what diffs to use:
Those from the HB lightning or those from the HB lightning PRO? What's the difference between them anyway?

Second is the gear transmission ratio:
I have absolutely no idea which gear ratio to use. I'm going to use a Plettenberg Bigmaxximum motor with 5S lipo, if that helps. Hope someone could give me a hint there.

Third question is which batteries to use:
1x 2S + 1x3S for weight-saving or 2x5S for doubled run-time?

And the last question, for the time being, is the one I forgot while typing this text here

Thank's a lot everyone,
Jo