so new here, male, 45, WA
questions
1. why is my neck the favorite spot for my 11 wk old?
Because it's warm & has a nice pulse. Yorkies can be catlike that way.
2. biting cause he misses me or just a puppy
He's a puppy, but need to curtail the biting ASAP.
Give a toy instead & praise when he chews that instead.
3. no crap this is a rottie soul in a yorkie body (had rotties my whole life)
Yorkies are a huge dog in a little package. All attitude! 
4. at 11 wk is humping everything in sight good for his ego or mine?
This is puppy play & figuring out dominance.
5. should i use a prong collar for training? (JUST KIDDING)
Oh, HELL no! Don't EVEN kid about that!
6. where the heck do i find a harness that fits? wait till he grows a bit?
There are many adjustables, even cat harnesses. Look online too. Never use a collar on the leash.
7. does anyone else worry about squishing him if i sleep with him?
They figure out where to go. No, squishing is not usually a problem.
so last question, i came home the other day and found my wife in bed with my best friend, after i left and went to the bar, had a few, came home and talked to her, i sat looking at my jeep in the driveway and really reflected on things............................................ .................................................. ..................so should i get new rims?