Nimmy, while thats an amazing idea and something that probably works really well for you guys
theres just too much variation in school board and school specific policies when it comes to FIRST. Our teacher-mentor has to fill out at least a dozen pages of paperwork for each regional we go on and we in turn have to fill out just as many to attend them. In my last three years of high school, I was lucky enough to have teachers understand the amount of effort that I put into school and when it came down to the end, especially for university marks and scholarship potential, they were generous enough to allow me a 0.5-1% bump up, unofficially speaking of course. But throughout the entire year, the only classes I missed were for competitions. I never skipped a single class for robotics. Even if you are dead tired, at least show up and explain and see if you can absorb any sort of information. If you are cordial and polite with your teachers, preach the values of FIRST to them, no self-respecting teacher is going to stop you from putting your best efforts into it. Just remember that no matter what, academics should come FIRST!
You work hard, you play hard when it comes to the regional competitions. Spend the time during build season either at robotics or working. It is very very hard not to do things with your friends during this time, but the payoff is well worth it at the end.
As for attending robotics while in university, the great Shawn Lim, my boss and now a fellow alumni mentor at 188 explained to me that it was going to be quite difficult. It was probably more compounded for him since he attended Kettering =P. I am lucky enough be in international business, with only about 15 hours of class time a week at York University, which is only about 30-40 minutes away from 188's home base. I commute back and forth on free nights, usually Mondays, Thursdays to Sundays. Almost makes me feel like I am a high school student again.
Also a final note to new college mentors like myself, remember your police checks!