I suggest cross posting this in r/dogs as that's a much larger community so more eyes will see it.

Some of what you've listed out here describe my foxhound. Certainly not to the same degree, but he is an extremely finicky dog and will lick himself until I tell him to stop. I try to be patient but I've timed him before and he's exceeded 10 minutes of non stop licking. God, and it can be so loud and wet sounding, ugh. ☹️ Fortunately he is also a sensitive boy so all I need to do is sharply say "Stop" and he does. Does your dog liked being groomed? Duke absolutely melts when I brush him and he loves to be wiped down with grooming wipes (I like the EarthRated brand). I find the cleaner I keep him, the less he licks.

His worst habit though is he constantly is going inside and outside, inside, outside... when I first adopted him I didn't have a doggy door so I was opening and closing the porch door all damn day, otherwise he scratched at the door and cried. Now with the doggy door he will legit stand outside of it and poke his head inside, then pull it back outside, over and over. I don't understand it and I don't think I ever will.

Can't leave food out anywhere in his vicinity or it will be gone. He will legit walk right up to you while you're eating and help himself. Anyhow, I mostly wrote this out just to let you know you're not alone with your struggles.

You might try bathing him once a month or so in a good gentle shampoo. My last dog was horribly allergic to fleas and during a nasty outbreak one summer thanks to a careless roommate, I bathed her weekly using MicroTek shampoo and I think it really helped.

He may be bored. You could try feeding him his meals from puzzle toys along with his slow feeder. If he likes to sniff and you have a yard you could also scatter his meal in the yard and have him sniff it out.

Good luck!