WL_h8ter I don't mean to be a jerk but all the answers to your questions can be found in this thread and the driver circuit thread Daedal linked to above.
Don't rush and take your time to read both threads. Once you have read them read them again and then post any questions you may have.
Most members here will do their best to help you but you need to help yourself a bit first ;D
1.: 3.0V or 3.6V I read that when fully charged, a rechargeable 3.6V might be up to 4.2V - If I have two of these (=8.4V), is that still fine with the LM317, or should I get 3.0V rechargeables?
While I don't give a stinkin' thing about the "police" label, the case seems really rugged and well-built, and if the lamp is crap then I couldn't care less. Also, if I would succeed making the Aixiz (= DX-module ) watertight, then I could possibly have a waterproof laser - which would be a really cool gizmo! Talk about swimming, diving, cooling
But it is especially the fact that 2*CR123A, solid case and low price are combined that makes them most attractive to me.
2. Any will work as long as you have the creativity and the motivation. I chose the one above for the guide because it's got a nice big head that can allow for enough room for anything to happen int here nicely
well, kinda stupid situation, but I can't seem to find a satisfying charger for 3.0 V on DX (satisfying = not slow not overheating better multiple cells overcharge protection automatic cutoff low price ) - so can I modify your driver to work with 2*3.6V too? Or are 8.4V killing it (Well, gonna try it)?
I mean, if you say to better take 3.0Vs, I will, just if there is a way to either get 3.6V working or a "solid" 3.0V charger, I would like that.