Libernull is correct, using copy and paste on the "body" of each will synchronize the dials. Works nicely with the morphing clothes at DAZ. However if the morph dial isn't there, it won't do much of anything.

Most clothes stay close to the default figure shapes, the better ones have morphs to match the standard figure's morphs. Taking notice to what morphs you like to use, and which ones are offered in an item of clothing, will give you an idea of how much tweaking you will need to do.
Just about everything I have ever bought has fit perfectly on a stock figure, the problem is, who uses a stock figure?

The Tailor IS relatively cheap, magnets are free. With the help of the tuts here and the other top Poser resources, one can be fitting their own clothes in no time.

Oh as far as selecting the parts, you can select them from the menus under the document window.

My guess as to why most Poser renders are nude...

...It would be a shame to cover all of that work up.