Unless I'm mistaken, when you said you can't always get the clothes to fit, stupidest_login_ever thought that you were not matching morphs on the figure. That's what the Tailor is for.

For the material room, here's a beginning tutorial on how to apply textures to a figure in the material room. http://poserpros.daz3d.com/forums/viewtopic.php?t=6969
When you apply in the Pose room, you're using MAT files someone else has prepared. That's fine for something quick, but you're losing a lot of power and you're at the whim of the creator. Furthermore, if you want to make textures yourself, you're going to have to know how to apply them, and if you want to distribute you should know how to make MAT files.

Stew has a material room FAQ here http://www.keindesign.de/stefan/poser/firefaq.html which you might look over as well.

If you want to make something in Poser (an image, a new clothing design, a new character for a figure, whatever), you have to know what you're trying to make, just like PSP. If you treat it as "just doll theater" and refuse to learn any of the advance capabilities because they're too hard, it's not really fair to blame the program.