RcMonster diff question

I've make an order of $500.00 + yesterday just in revo and motor parts, so i'll wait this winter to buy a set of this diff. I'll put RD racing aluminium diff cup and just see how long they'll hold, and when i'll break one, i'll put the RCM diff.

Tell me something about Neu motor, which one will be best suit to run on 4s li-po in my revo??

1515 or 1512?? and which wind ? 1Y, 2.5D ... is i'am better to take a smooth or fined can??? don't know anymore about Neu.
Because this winter i want to buy a 16018 MGM controller and upgrade to a better motor. And i'll put the MM controler and feigao 12L in the crt.5

Thank you!

David