And can I mod a body and set its UVs the same as M3 / James so that the textures are compatible? Would that be somekind of copyright issue?

It might be. You should probably run it by DAZ/CL first.

And can I use James as a base for modding a new figure (keeping the UV's same)? Would that lead to some copyright violation? Coz that would really save a lot of time!

I would think it would be okay, as long as you RTEncode the OBJ.

Poser used to be all freebies. But with the dot-com crash, it's become expensive to get the kind of bandwidth you need to host Poser freebies. You may discover this for yourself when you try to find a host for your head.

Many of us Poser users don't do real modelling on our own. I can't afford Max, and I doubt I ever will. I do use Anim8or, but am nowhere near proficient enough to make my own figures. And it takes me a long time to make a prop. So when someone asks me for something, chances are I'll direct them to the MP. Of course if I know of a free item that does what they want, I'll recommend it, but more and more things are MP items now.

IOW, we are telling people how we do it. Which is usually to buy the stuff.