I personally wouldn't use it, however think it'd be a very good idea. I personally have always liked mathematics and enjoyed working on long and difficult sums when I've nothing to do. Most likely somewhat boring for others, but it keeps your mind sharp.
It'd be a nice venture for you, and I'm sure it'd be worth it in the end if you did it correctly and targeted the correct people, etc. etc.
It's a good idea - You should look into it more, and maybe even pursue it.
In regards to the forum board, I'd have to say it'd be best to go with phpBB. Regardless of whether it's free or paid - I'd much rather go for phpBB anyday over IPB, and would most likely do the same over vBulletin. I, personally, want a forum board which is fast and isn't bloated full of features such as IPB and even vBulletin. If you don't bloat phpBB, it is very fast... but no matter what forum board, no matter how good, if it's bloated it'll always be slow.