The closer you live to campus, there is a greater proportion of undergrads/loud parties/etc. Some apartment complexes are worse than others, such as Cedar Village (a Rose Bowl riot took place last year) and Chandler Crossings. I had some friends who lived in Capitol Villa apartments just east of campus and they seemed to like it. Or if you decide to rent a house, they are located mainly north of campus, and generally affordable.
Traffic noise isn't bad at all. The busiest road is Grand River and it runs along the northern most part of campus; it separates campus from the bars/clubs/restaurants/shops of East Lansing.
The CATA buses run regularly throughout the day. There are many different buses and bus routes, so depending on where you decide to live, they will come more or less frequently, and you may have to walk a longer distance to get to a bus stop - it all depends. In my experience, I've never had to wait more than 10-15 min for a bus.
Another thing, campus, and East Lansing in general, are very easy to traverse by bike. This will probably be your primary mode of transportation in the warmer seasons. MSU has its own bike repair shop, and the MSU surplus store has a giant bike sale every fall around when the semester begins.