@ Erwin0265: I don't promise that these are definitive answers to your questions, but here goes!

For a simulation to work, there needs to be a period of time for the cloth (or hair) vertices to 'relax', come under the influence of gravity, collide and so on. So, even for a static pose, you will need to run the simulation over a number of frames. It may be possible to do this with the figure in its one and only pose but - as with Poser's Cloth Room - it may often be better to let the figure arrive at the desired pose over a number of frames. I generally start from a T-pose, even for animations where frames are derived from the Walk Designer. Where a figure moves abruptly into an extreme pose, there is liable to be penetration of the figure with the cloth mesh if default settings are selected. (I'm thinking of a high-kick in a long dress, or something extreme like that). Also, if the figure is in a pose where the clothing penetrates it at the outset, then the chances of getting a good final drape are much diminished.

You can bring more than one object into the simulation as a Collision item. A figure wearing a tight top could perhaps be brought in as two collision objects for a hair simulation if the cloth top conformed well. Otherwise, if the top is loose fit, it may be necessary to run a simulation where a top would be a clothing item and the figure would be the collision item.

THEN a second simulation would be run for the hair where the figure and the top_VWD objects are collision items. What is the top_VWD object? After a simulation the original top is invisible in the Poser scene and in its place is the mesh produced from the simulation with _VWD added to the name. That can be chosen as a collision object for the hair simulation.

Running one simulation for both cloth and hair together isn't possible, as far as I can tell.

I agree 100% with Biscuits' comments.

I can't remember if I linked to this already but HEREhere are some of my efforts.