Questions about EVERYTHING. Please help.

Hey guys. I'm a runner currently training for a marathon, and I'm taking up swimming for my cross-training because I'm sure you all know it's excellent exercise (also, to be honest, I want that six pack that only swimmers seem to have). However, I haven't really swam since my parents threw me in some class when I was 5, so I'm kinda lost right now. I have a friend that is a swimmer (she's actually swimming the English Channel later this year), but I feel bad hounding her with all these questions, so I thought you guys might be able to help. My questions are the following: 1) Swimwear (male); what is the best? What do I want to look for? What do I want to avoid? 2) How the heck do I even start? What do I need to do? I obviously need a membership to some pool and a swimsuit, but outside of that, I have no idea what I need. 3) How do I actually swim for exercise purposes? I think I know most of the basic strokes, but I'm somewhat at a loss as to what is better to exercise with. 4) And last, but not least, how do I start swimming? In the sense of how long should I start out swimming for? How many meters? Is swimming like running in the sense that you just go until you can't anymore, or is there a better way to ease myself into it? I realize this is a lot, so I thank you guys in advance for your help. I really want to get into swimming, and I'm excited that I'm finally starting.