Punisher: Yes, static stretching can cause problems, because you need warm muscles for them. Which is why I do a dynamic warm-up routine that takes about 5-10 minutes (and also enhances my flexibility). Plus doing calisthenics is like doing a dyanmic warm up in a way. As far as the bridges go, they are amazingly effective so long as you do them right. Sadly, there are a lot of misconceptions about them out there, the most prominent being that you rest your weight on the top of your head. You need to put the weight on your forehead.
Boyd: You asked for a good resource for bodyweight exercise, I'll tell you what I got. I got the book "Combat Conditioning" by Matt Furey. his website is www.mattfurey.com if you check it out, you'll see a lot of bullshido-esque claims on there, and you'll realize that he's just trying to sell you on a lot of crap. But Combat Conditioning is well worth it. I would recommend it. And for you Punisher, that book also has detailed instructions on how to do proper back bridges and front bridges..... and let me tell you, after doing proper bridges for a few minutes, your neck will NEVER have felt so loose.
--A poor band player I was, but now I am crocodile king. --