PE/IB question and Prep Question

It seems like everyone on here wants one thing: PE. I realize this is a generalization, but really, it seems like 90% of the posters on here are college kids or analysts who want to make it through two years of Banking and then work for PE. It seems like working as an associate, VP, or MD at an IB is looked down upon. What is the actual difference in lifestyle/compensation? I knew this has been asked a ton of times but reviewing compensation in the different fields they seem comparible, and I imagine they do just as much gruntwork and modeling as investment banks. Does the same hold true for M&A? I think banking sounds pretty cool, and PE doesnt sound much different from what I read about it.

My second question (and more important to me): If I have a year before I start business school (deferment due to military commitment) what would be the best thing to do to better prepare for a banking internship in my spare time (I will only have a 40-hour work week)? I talked to a friend who did not get an offer at a top BB M&A group, and he was coming from H/S/W. He said it was his lack of excel & powerpoint skills that hurt him on top of being in the most competitive group. I hear a lot about Wall Street Prep, and was wondering if taking the course in my spare time over a year would be the best thing for me if I wanted to go into my summer associate gig (God willing I get one) knowing how to properly build/tweak models like any other seasoned analyst. I am an engineer with a masters degree, so technical stuff doesn't scare me--I just don't know where to look for the information.