On the tail, you might want to make some rattles (pieces of material with gravel in them) so that when he wants he could shake his tail & it would rattle.
I have seen some reptile looking prints, usually kind of "slinky", stretchy fabric in the clothing/garment area of the local Joanne and Hancocks. If you could find something like this just make a tube with sort of a hoodie to go over his head and make a really long tail and of course, a red felt forked tongue!