What is the better device a Kindle Fire or Nook Color? Or is there a better device with a comparable price?
Well, when you ask how much trouble it would be, ask yourself who you might be in trouble with. That is a question for whomever is in charge of enforcing the fire code in your area. It can definitely be done, but the protection system you will have to replace it with depends on your local regulations.
Personally, headlamps are not a a good idea. I hate running with anything on me, even a watch. A headlamp is heavy and it could get very annoying. I don't want to discourage you, but I wouldn't. Handheld flashlights are good as long as they are small and lightweight.