What Can I Do With A Jailbroken iPod touch?

I have a couple of questions about jailbreaking my iPod:
-What does it do?
-Can I put my DVDs onto my iPod if its jailbroken (I’ve wanted to put my DVDs onto my iPod for a long time but Handbrake didn’t work for me, will making it jailbroken allow my to put my DVDs onto my iPod?
-Will it harm my iPod?
-Can I restore my iPod if I don’t like it?
-Any other important information please would be appreciated.