If I were to stay in Munich, Germany for 3 months (June to Sept), what kind of clothing would be comfortable given the summer/autumn conditions?
From this Wikipedia page you can get an idea of average temperatures in Munich. From there you should be able to figure out which type of clothes to take. A rain protection is important, even in Summer. Take an umbrella and a raincoat adapted to the season's temperatures.
What you should wear at home eventually depends on you. It can range from nothing at all to whatever yo want, as long as you feel comfortable ...
At the office, it depends where you work. You can enquire wiht your (future) employer about dress code. It's different from place to place.
For College, you can choose an informal dress, unless you are attending a business school. In that case a more smart casual dress might be appropriate.
You need to bring a variety of clothes with you, since there is no typical German summer. Especially during July and August you can expect quite hot periods (up to 30 °C and more) where shorts and T-Shirts are the best clothing (unless of course business attire is required). However I wouldn't bet on these 30 °C. I've experienced summers (or periods during summer) where you had 20 °C if you were lucky. So you should also pack in Jeans and a sweater of some kind. That said, rainshowers are always a possibily and especially on hot days you should be prepared for thunderstorms.