heres a couple of your questions answered. But by the way GREAT looking mali cage, I used to keep them and they are GREAT and your look fat and happy!
1)Some people say they need UV some dont. I dont use UV and my Henkeli are just fine. But if it worries you just use it as it cant hurt them!
2)I have feed my Henkeli wax worms every now and then. Never feed meal worms. But I wouldnt give them many wax worms as they can get addicted and only want to eat them. You probabally would be better off to feed them maily crickets with wax worms, but feed wax worms to them very sparingly.
3)Im not sure what kind of basking temp they need as I dont keep them but I would think about 85 degree basking spot with a 70 degree cool side as they will go back and forth and find what temp they like!
4)Yes I do beleave that all leaf-tail geckos tails will grow back. But If you feed them as much as they will eat that would be fine. Just give them all the food that they will eat as they will tell you when there doen eating.
5)A water bowl would raise humidity but you would still need to mist there cage. Just make sure that the water bowl isnt deep enough for them to drown.
I hope that this helps! And you could probabally keep a pair in a 10 gallon cage but a 20 tall or long would be better though and also would allow you to get more if you ever wanted to! LoL thats always my problem! Hope this helps, and Good luck if you get them! Erik