set up for BL revo.

so a ubec, is a little device i that i connect to the battery pack set up, and plugs into the reciever? and i have to cut some wire on the esc that goes to the reciever?

where do i get a ubec? and how do i wire the bl set up properly?

which pinion should i use on the stock 40t spur, like tooth wise? 10,11,12 or w/e is recommended. ?

so a 8xl with 14cells, on a mamba max or 9920, which should i do ? what pinion tooth wise and how do i find the size of the shaft on the motor?

where can i find a 8xl, mike dosent have any on the site store. well not 3 wire ones, only 2 wire ones. ?