just some first, quick observations (no Poser at hand at the moment):

 - cloth sim does no recognize displacement maps. So when the wrinkles in the pants are made that way, the cloth needs more room to move

 - collision offset and depth are measured in mm (millimeters). So .5 is not very much. You do need to set depth appropriately as well.

 - the sim is sensitive to the speed of movement in any animation, used to get your character posed. Note that 1 second takes 30 frames. Some people make their character move from standing up to seated down in 1 frame, so their butt moves 40 cm in 1/30 of a second, that's 12 m/s, with sudden start and stop, while wearing tight leather pants. If you can't make the move in real life, then you can't make it in cloth room either.

 - self-collision manages collision of shirt vs itself, there hardly will be any in your case. But you definitely do the two other options.

 - you might consider more (=smaller) steps-per-frame.

Generally, http://www.book.artbeeweb.nl/?book=cloth-room holds my cloth room tuts.

Let's hear if anything of this makes sense, so we can help you further.

best regards, have fun.

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though