Anne
Good question about sleeping position and shoulder and neck pain.
My advice is for sleeping position: use pillows to your advantage, and make sure they're not too big.
A pillow between your knees when sleeping on your side could make a huge difference. The alignment in your knees and hips can affect your neck/shoulders.
If you do end up sleeping on your back, make sure your pillow isn't too high, which will put your neck at an unusual angle. Even on your side, if the pillow is really big and firm, it may be too high. Evaluate how your spine is aligned from the side, once you are laying down. Those curves matter, too.
As for poses to help with neck strain upon waking, don't underestimate standing poses. If you energize your body with Front Warrior or Warrior 3, your neck may naturally soften.
Bridge pose is also good, as it puts your neck in neutral and you have the floor to support your head. Just keep the bridge low and gently press your elbows down towards the floor.

And, Anne, look for postings about Kari Tomashik's next yoga workshop at MBG, since you found that experience to be beneficial in the past. She will most likely hold a workshop this fall.
Good luck!