Re: Yoga and its benefits
You've come to the right place. I'm training to become a yoga instructor right now, actually. I love yoga. When I started it, I couldn't even touch my toes. Now I'm very very flexible. It is a fantastic practice that really helps me relax. The tools you use in yoga classes (breathing, stretching, etc.) can translate well to life. Sometimes when I'm really anxious, I find myself using the breathing from yoga to calm myself.
I am in much better physical shape than I was when I started. Flexibility is one of those things where if you don't work on it constantly, you lose it. And once you've lost it, you become open to being injured more easily in everyday activities and exercise. As for yoga being enough on its own, I always try to discourage this idea. Yoga will help with flexibility, and it will help build muscles though isometric exercise. If you really get going, you can work up quite a sweat. But as much as I love yoga, I think it is part of a balanced routine that involves cardio and strenght training.
I really encourage you to give it a try. At first it may feel strange, and you'll be really sore afterwards, but if you stick with it, you'll start to see a major difference.