Here are the steps that I use to load the David bodysuit in Poser 6.  I've used Michael's name in the explanation below, but I think that these steps will work for any of DAZ's figures.  You can use them for any type of conforming clothing.

I don't have Poser 7, but I would imagine that the steps are the same (a Poser 7 user can correct me if I'm wrong):

1.  Load Michael into the scene.
2.  Find the bodysuit in the Figures library.  It should be in the Michael Morphing Clothing folder.
3.  To load the bodysuit into the scene, you can either 
     (a) click on the bodysuit thumbnail once to highlight its picture; then click on the "create new
           figure" button on the bottom of the library palette.  The button should have two
           checkmarks on it.  This will load the bodysuit into the scene.  It may be hard to see parts
           of the bodysuit at first because it's taking up the same space as the Michael figure or has
           loaded slightly behind it.
     (b) double click on the picture of the suit.
4.  If you want the bodysuit to fit onto Michael, select the bodysuit by clicking on it.  Then click on
     the word "figure" on the menu at the top of the screen.  In the menu that appears below the 
     word "figure," go down to the words "conform to. . ."  A pop-up menu should appear.  Make
     sure that "Figure 1" (or whatever you called Michael) is selected. The bodysuit should then
     drape itself over Michael.  You can also set Michael's pose first and then use the "conform 
     to. . ." command.
5.  If you want the bodysuit to have a certain preset design or texture, then make sure that it is
     selected by using the drop-down menu above the preview window (it should have Figure
     1 or some other name with an upside down triangle beside it).  Select the pose tab in the
     library palette on the right.  Then find the !MAT Michael Bodysuit folder and enter it.  When
     you have found the picture of the style you want the bodysuit to have, click on the picture
     once. Then click the "apply library preset" button below.  The suit should then take on the
     right appearance. 

I hope this helps.  I'm a fairly new user of Poser as well, so I can understand your frustration.