You can't edit the meshes in Poser, but you can apply textures to your liking. The editing of the figures is constrained to the morphs built into them. You can build very crude things with the Poser primitives (sphere, cube, cylinder etc), but not do any modelling as such. V3 is a stand-alone figure sold by DAZ (www.daz3d.com). She is not essential for Poser (you will get a bunch of figures with the package) but she is the most advanced and versatile female model around. A lot of free and commercial add-on stuff is made for her and, yes, you need to get her before you can use any of these add-ons.