ratscloset would be the one to know about products over at CP.  I was going to suggest VTC.com, they also have a Poser Video.  Poser 5 Demystified is yet another video, that would take you through all of the Rooms.

If you click on my Avatar's homepage link, you will see a male and a female character.  The male is Daz3D's Millenium Man Michael 2(M2 for Short.)  I think he is the best male figure for Poser.  For a good look at him click on the Lips in my Signature.  Daz3D does also have David 3, whom is a nice second.  Just do'nt confuse M2 with M3, they are totally different.  Recently, RuntimeDNA, has introduced an Ultimate Body Morph Set, for the Poser 7(P7) default figures.

The Female I use is Daz3D's Millenium Woman Victoria 3.0(V3.)  V3 is Poser's best female figure!  People will be foaming at the mouth to point out that Daz3D Millenium Woman Victoria 4.0 has recently been released, but they are two totally different figures all together.  The distinct advantage V3 has over V4 is several years of Artists' Communities' development(Magnets, Morphs, Textures, Hair, Etc.,)  where V4 was just released 2 or 3 months ago.  Untill a week or so ago, V4 also did'nt have any of the Muscular morphs Daz3D is quite famous for(With M2, D3, and V3.)  So, V4's Musclular Morphs have finally been released, but I hav'nt tried nor seen anything compareable to V3 yet.