1999 Chevy Astro Power Stering & Brqke Problems

While trying to back out of a parking space during a snow storm, My brakes became hard to press with little stopping ability and my power stering went out at the same time. I've asked several garage repair shops and nobody has an answer. I understand that my braking system is connected to my power stering system. I also hear the term brake booster tossed around as well as it may be a vaccume hose. Please help. Also is there a diagram anywhere that will show these systems and how they connect? Final question: Where do I find this vaccume hose? Thanks for your help.