Dave Mason was the player on Watchtower I had in mind. I had thought he played the wah-wah lead, but you may be right van lingle.

And GP was indeed the answer to 11. He and Richards were quite tight at this point, a relationship that Jagger resented. But the country shift in the Stones sound at this time was largely a result of Parsons' influence. Even Jagger's country drawl (Girl with the Faraway Eyes) was supposed to be a tongue-in-cheek Parsons impression. Several songs, including Dead Flowers, Let it Bleed and Wild Horses, are rumored to have been penned by Jagger and Richards with GP's input.

That leaves #2. Any more guesses?