Alright, I'll share a tip that
Nike Davies gave me, use a piece of upholstery foam. Cut it into a rectangle then trim one end to be a tip.
I would say that an 8 yr old can work with hot wax & supervision. I did my first batik project in Girl scouts at about that age. Don't think I'd trust a 4yr old with the hot wax though. I sometimes scauld my fingers & I know my 3.5 yr old would NOT be happy if that happened to her.
If you just doing bandanas or something glue works fine. Dharma also sells a resist that works with hot water dyes (Rit type). It's liquid in cold water but hard & resists when in hot water. This is also very easy stuff to get out. Well compaired to real wax it's easy to get out. I have also never had trouble getting school glue out in the washing machine.
Have fun.
Chole