In regards to GST I'll do my best to help. Is it sandable? I wouldn't know, I haven't had to try.
For the drips it's pretty simple. Keep in mind I dip cranks though, not spoons. A few minutes after the bait is dipped I run the tail hook hanger along a paper towel which seems to "wick" off the excess sealer. I usually hang it again for a minute to see if it's done dripping. If it is, I clean the hook hanger holes with a tooth pick and hang it to dry. Now, in regards to spoons, I would be careful wiping the spoon itself against a towel or piece of paper to get rid of the excess. The GST gets into the paint (createx) and makes it soft. If you touch the surface itself on anything before it's dry the paint will come right off. For me I'm not concerned with the paint coming off the rear hook hanger, that will happen with use anyway. I have tried to flip the lure while it's curing but it doesn't work. Basically for me the GST dries before it drips back off the other side causing runs that harden. You could try a lure turner? It might help level things out while it cures?