Noob, the term is noob
MMM = MambaMonster(Max- this part was dropped officially but we still use it to avoid confusion with the MM- MambaMax).
The MMM system is worth every penny and more, if stupid fast and powerful with almost limitless adjustability is what you're after. The novak systems are good for what they are- old systems given a few tweaks to update them, but they lack the power, adjustability of versatility of the MMM in so many departments its just not funny; I've had both, and the MMM esc wins hands down, as does the MMM motor (CastleNeu) by all accounts.
The MMM is drop in yes, all you will need to do is buy a few pinions, and solder on the battery connector of your choice; at worst you will need a buy a series Y-harness so you can run a pair of 2s or 3s lipos, or a pair of 7 cell nimh packs for example.
Gearing will depend on your voltage/ batts.
Wet conditions should be strongly avoided- the esc has a special coating on the circuit board (PCB), but the connections are not water proof, nor is the esc case. At best you could run after its stopped raining if you do a little work to shield the esc (shower cap, balloon etc over the esc or electronics), and snow running is okay if you do the same; doesnt take much to keep out some snow, but running the truck when its very wet or through puddles is just asking for trouble- its a $300 system, no need to try and kill it for the sake of having some fun.
To learn more about BL and lipos etc in general, and how to setup a truck, read my wonderful FAQ in my sig- the Emaxx one may be down, but there is also one on my website, or the erevo one is basically the same, just a few minor differences due to the size of the lipos you can use on that truck compared to the emaxx.