As far as number three can't you create the pose you want for the cloth such as sitting down with a larger person, spawn a morph from the position and then apply that morph to the cloth then save the cloth back out as "large sitting"? That way next time you already have the cloth in a sitting position and you can apply it then have the character stand up from the sitting position. Granted you would have to save the character pose as well since you would want to make sure the figure is inside the cloth, which is the reason for starting in the T-pose as that is the position of character and how the cloth was first modeled, but it should work.

Poser 5, 6, 7, 8, Poser Pro 9 (2012), 10 (2014), 11, 12, 13