I got those at Performance. There are a few Shimano variations on the same theme that are always in stock there. Google "Campus pedals" and see what comes up.

You will get to and from school quicker with stiff-soled shoes and clipped into your pedals. 5-15 minutes over 25 miles? Maybe. Depends how quick/slow you're doing it now, how often you have to put your foot down, how much climbing there is etc. It'll definitely help you enjoy your longer weekend ride more.