I agree with @ghdprentice :
Use 10 gauge regardless of length. Sounds better I am told so why not?
At least 2 dedicated runs but I did two and then did two more!!! So do four and be set.
I did not spend a ton and used PS Audio outlets. They grip great. Many opinions about more expensive outlets, I did not go there.
I used some special silver grease in the install of my breaker, supposed to enhance conductivity and not expensive.