I see no reason why there would be a difference between 10, 12, 14, 16, or even 18 AWG. All of those gauges can easily handle the signal in a speaker cab. The wire in the speaker itself is tiny. The wire inside the amp is also 18/20/22 AWG. If you have a long run from amp to cab, then sure... use thicker wire. But the 14 AWG I used inside the cab is perfectly fine.
My Bogner cabs have that huge 10 AWG stuff and it's a pain in the ass to work with. But I keep it in there just because.
As far as wiring, you should be able to see what I did in the photo.