Well, a lot use 2s lipo, allthough 3s are more common, not all the esc are fan cooled, look at tekin. I even ran brushed in mine for a couple of weeks to get it moving while my stuff turned up, also im the states for some reason a lot do used brushed systems fxr for example, a lot depends if you dont use that much like once a week, it may last a long time, but then a re buildable brushed is better to replace the brushes, but in the long run you will buy sooo many brushes itl be thecost of a brushles.
Coging is never an issue if you use your dig properly, engage and disengage as a matter of course then it wont happen, its only the differnce in front to back missing there gear ratio, sorry not explaining that well to today, too much meds... If you engage and dissengage your dig you wont get it, know very few people who do when using dig properly.
Si, ill see if im gonna use my tekin stuffin my new build if not ill bung it in yours, its the 17.5t
My new crawler is brushed so i may not need the other stuff.
A lot of stuff is all about the name being better, sometimes it is, but there are a lot of non branded esc and motors made by the same companys, usually with lower or no settings as a result, this dont matter in a comp as you dont need a drag brake, the worms are your brake.
It is poss for what your using it for mate, you could bung a brushed in, if you have stuff spare just try it, you will only kill it at worst,lol.
But you will need the saddle pack lipos, again for what your doing 2s will be fine, and they are only bout 30 quid.