When it comes to exercising, doing the right kind of exercise is the most important part. You actually don't need to do that much. Read "4-hour body" and look into high intensity interval training (e.g. tabata sprints).

Here's an earlier post on weight training. Some of the top comments are really good. By eneasz:

my biggest piece of advice would be to not worry at all about optimizing anything until you've first gotten into the habit of regular work outs, and actually enjoy it. Only then should you start optimizing in other ways. The biggest obstacle is always sticking with it.

and by jswan:

Book recommendations:

another vote for "Starting Strength" by Mark Rippetoe "5/3/1" by Jim Wendler. Available here: http://www.flexcart.com/members/elitefts/default.asp?pid=2976 Answering your questions:

1) It doesn't matter that much what you do, as long as you stick with the basic, multi-joint movements (see below); what's more important is that you do it consistently for a long period of time (i.e., years), and you train progressively harder as you make progress. That said, you need to avoid injury. Training with weights near your one-rep max is riskier as a beginner, especially without a coach. I like the set/rep progression laid out in the 5/3/1 book listed above. I've made good progress on it after doing regular weight training for 15 years; it's difficult to make progress at that "training age", so it should work even better for a beginner.

2) In general, you should strength train at least twice a week but not more than four times a week. This does not include conditioning or mobility training, which you should also do.

3) Don't bother with supplements. Spend your money on a clean diet with lots of protein and you'll be fine. Since you probably won't take this advice: creatine monohydrate seems to have the most evidence in favor of its efficacy, but the effect is still relatively small and seems to vary between users. I haven't noticed a difference when using it.

Remember that there are only a handful of great movements: squat, deadlift, bench press, overhead press, pull-up, push-up, dips, rows, power cleans. Consider the barbell, dumbbell, and bodyweight variations of these and you will have plenty to do without doing a bunch of exotic isolation work.