Emaxx questions

I have decided on a feigao 8xl/mm combo, along with a BEC, single speed conversion, new idler gear, heatsink and fan. I have upgraded the drivetrain to 3.3 specs. I have a few questions:
1) Will the transmission hold up to this motor/esc
2) Can i run this combo on 12 cells?
3) Will i need to upgrade the diffs further if i only run 12 cells at first?
4) Will i have any overheating issues?
5) Are there any more upgrades i should be considering?

I don't care as much about speed as i do about durability and reliability, and i am on a budget. Thanks for any responses.