Hey Klym,
Thanks for your letter. It sounds like you're taking all of the correct steps to jump start a career in the industry. Your education is a big part of the puzzle. Nobody wants to hire a dummy and a solid degree is a good way to show you're not in that boat. Specific classes really depend on what job description you are shooting for. Like any industry, this one employs everything from accountats to sales people. But generally a well rounded business education with some solid focus in marketing is your best best. This industry is heavily marketing driven and a solid understanding of that helps in any position.
While what you know is important, perhaps more important is who you know and how you know them. Managing your skate shop's team is a great way in for meeting folks and getting some solid experience. Try to learn as much as you can from the owners and managers of the shop as well. Get a solid understanding of retail cycles, demand, ordering, and constantly ask questions. Let them know your interested in diving in and they can help mentor you and introduce you to reps and other folks they know. Try and meet as many people as you can in the industry without being stalkery. You never know which connection will be the right one.
Good luck!
Mike