Twin Force Brushless Questions

Hi All!

I am a new rc enthusiast and this is my first vehicle.

I have a Twin Force and want to set it up with a brushless motor, ESC, servo, and Radio.

I have already decided to get some gp3300 6 cell packs so I will be running this on 12 cells for now.

I am looking for the decent speed right now, with good runtimes as I learn to drive this truck with the stock parts, and also the ability to go much faster later once I upgrade parts and run more cells.

What motor and esc do you recommend, and how much speed and runtime can I expect?

I have been looking at the Feigao motors as they are pretty cheap, but I dont understand the differences between the different numbers, 8L, 9L, 10L, 7xl??

I'm considering getting the Hitec 645 high torque servo and the Airtronics MX3 radio, good idea?, better options?