The fabric paint won't get sticky of you let it completely dry for a good 3-4 days. It is machine washable so it shouldn't get sticky. I am gonna get the EZ shape stuff because I want to use it over the top of Mylar tubing for making Mustad minnows. I do not think that the fabric stuff will work over it and still give a clear look to it like you want.
Hard as nails will work to protect it, so will epoxy. Both will make it hard which is something I don't like on a jig/fly. If you just want to get a bulky body like that true something I have done for a while, colored hot melt glue sticks. Very tough but you really have to get the knack for keeping it round as it will drip off very easily until it starts to cool.
I love taking my kids fishing, now if I could just manage to fish at the same time.