Ball Mount Question

That's debatable. Any WDH will "preload" the receiver. Once I've loaded the round bars, everything is pretty darn tight down there. We don't hear any clunks or thunks when the WDH is engaged, so my inclination is that it's somewhat redundant. OTOH, it would be kind of like belt plus suspenders, and the tightener is pretty inexpensive.

You can do it! 

If you're talking about the high torque settings for attaching the ball you don't need to buy a huge torque wrench. It's not rocket science.  Turn the hitch 90 degrees in the receiver. Put your socket and breaker bar on the ball nut and step on the breaker bar, being careful not to fall. If for example the torque setting is 250 ft-lbs (3000 in-lbs) and you weigh 250 lbs  step 12 inches from the center of the nut. If you weigh 125 lbs, step 24 inches out, if you weigh 175 lbs step 17 inches out. IOW, take the ft-lb torque setting, multiply by 12, then divide by your weight and step out that number of inches. Put all your weight on the breaker bar and bounce up and down a little bit just to be sure, it won't hurt anything. 

It's not terribly difficult to install, and there are easy workarounds for he high torque requirements (see above). We bought the E2 and the RP179 together as a  "package", and the dealer set it all up.