1)When do you know what aircraft you'll be in?
They'll tell you when they offer you a class date.
2)How long do you sit reserve in each?
Depends on your domicile. Most domiciles you won't sit reserve for more than a month or two, other domiciles might be 3-4 months. There is enough movement right now that you probably won't have to sit reserve for very long. And the reserves we have pretty much fly on every reserve day.
3)What are the odds you get to pick your base?
100%. Whether the base you want is aavailable is another story. Most new-hires in the CRJ have been going to ORD, COS, and SLC. We haven't have an EMB new-hire class in a while but Fresno seems to be the most junior base. Again there is enough movement right now that you should be able to get the base of your choice in less than 6 months.
Who's face is that on the south end of the north bound donkey? It looks like the guy in the cube next to me.