MrSkippyJ

You definitely don't need a line driver.

9volts of preout? i'd say you can very safely leave out a line driver.

all 4 in each drivers door?

where are you going to put them in the vehicle? What configuration?

Slash 4x4s are a pretty solid choice. They are pretty damn stable on 2s too.

Jato does pretty well on grass but it's not like a 4wd car. it's fast, a lot of motor on a small car.

Or the Traxxas Slayer is a nice option too, but it's a smaller truck than the Revo.

Tmaxx is cool but it isn't nearly as stable as the Revo. Many other brands to choose from that can be cheaper and probably better than Traxxas. I'm not too familiar with Nitro stuff though.

if you are going with Traxxas I'd personally go with the Revo 3.3

Is it the same amount of power?

Nope.

Are they separate electrical systems?

set it to the max undistorted level, then lower it until you stop hating yourself for using pro-tweets (last part is a joke!!) for real though, set it to max undistorted level and lower it (or keep it the same) until you like how it sounds and has the balance that you like.

You can't accurately calculate it, it has to be measured. You can guess just like you have been, but without measuring anything you come up with is a guess.

Just assume it does rated and use that value.