Enjoy the class - and prepare to be TIRED!
I took the Basic Rider course a few years back and loved it. It was a long and very tiring weekend, mentally and physically, so you might not want to make any other plans... It proved to be "not for me" (I don't trust my reflexes to be fast enough to get me away from trouble), but it was a great experience and I wouldn't trade it - or the "M" on my license! - for anything!
FWIW, as others have written, I sought a lot of advice about what kind of bike to get, and it seems to come down to two schools of thought: either (a) start with a smaller bike to get comfortable and then upgrade or (b) start with a somewhat larger bike (600) and then you don't have to upgrade. I'd lean toward option (a). Used Rebels in great condition are not hard to find, as people buy them and either upgrade or quit riding altogether.
But it all depends on your comfort level, and you won't really know until after you've completed the course, so the best thing to do at this point is keep a very open mind. You'll have a much better sense of it by then, and your instructors will have some good advice for you too.
Most of all, enjoy - and let us know how it went!
All the best! Vroom!
Cha Cha