I would like the throw in spot in the following scenarios: After goal A inbounds ball under B's basket 1.) Ball thrown length of court and goes OOB hitting wall behind A's basket.
2.) Same as 1 but ball hits court and goes OOB. 3.) Same as 1 but ball is touched by player and goes OOB

Looks like you have three scenarios.

1.) Team B inbounds under own basket.
2.) Hitting the floor doesn't matter. Team B inbounds under own basket.
3.) Ball OOB by which ever team did not touch the ball. OOB spot is where the ball goes OOB--just like a regular OOB call.