Bidding at Kellogg is pretty much the same as it will be at all schools. You get points and then you bid on the courses you want. 1st year you get 2,000 points and 2nd year you get 3,000 points. You bid on classes, if it has 65 seats and 100 people bid, you pay what the 65th highest amount was...so you could bid 1000 and be #20 but the #65 bidder only bid 350, and you only pay 350 and get 650 points back for the next semester.
Your first quarter, this fall, you get your classes for free. You will pick your classes and dont have to bid (thats why you get 1,000 fewer points). However, since you are MMM you will be taking classes winter quarter that no one else is really taking yet. I have friends who are MMMs who got their classes for like <10 points total during the winter...which means you can get pretty much anything you want in the spring.
You can take pretty much any class you want. However, like most schools you probably wont get to take every single rock star professor. The thing you need to do is plan out more than just that one quarters classes or else you might bid on the several popular professors and then have very few points left for the last quarter or something. If you prioritize what classes are musts then you will easily get the classes you want and can take most of the professors that you just have to have. In my opinion, bidding 800 points more for a guy who gets 9.6 vs 250 for a guy who gets a 9.1 is silly, but that is what happens with some classes. There will be one rockstar who bids for 2 to 3 times what other great professors go for...and the difference in quality definitely is not that huge. That said you can easily still get a rockstar or two for each semester. Some of the best professors teach classes that arent overly popular so they dont bid for huge points.
Don't worry about bidding yet, you will have plenty of time to figure it out. 2nd years will definitely walk you through the process...and its basically the same as you will deal with at all schools. I think the biggest difference is first quarter you dont have to bid on classes like at some schools. You will get all the classes you dont waive out of assigned to you (your can switch you schedule around if you want), luckily a lot of the 1st semester core professors are amazing, and the few that arent awesome if you are proactive you can switch.