Yeah, those 600s scream! We had a Honda F4i on ours (2001). During the summer we took out the restrictor and that car was a monster!! We did a few SCCA races and smoked every sports car we competed with.

To answer your questions:

1)Ground school will be covered as part of your education. Wherever you decide to go will most likely offer a package that includes books, interactive DVDs, and required pilot accessories.

2)No, 23 is not too late. I didn't start flying full time until I was 27 and I had plenty of time. I know guys well into their 30s and 40s that have made a career out of aviation.

3)What made me change? Well, I just loved flying I guess... After I got my private pilot certificate, I kept progressing to the next level. I still wasn't sure if I wanted to do it as a career, but after awhile I decided that I would really enjoy making a living out of it. So far I've been a flight instructor, a charter pilot, and now a first officer on a corporate jet. I love it, it's really a perfect job for me. I travel, I'm always learning new things, I enjoy the people I work with, and I have a pretty good quality of life. It would be hard for me to go back to engineering.

So, how do you get started? Start here:
flighttraining.aopa.org - Learn to Fly - Be a Pilot, Student Pilot Training, Flying Lessons, Flight Training & Aviation Resources

Also, download this ebook by Max Trescott for a good intro about getting started:
http://www.sjflight.com/LearntoFlyebook.pdf

What city do you live in? Maybe I can tell you some schools to visit.