Quote - Can a piece of poser (probably 8) clothing have more then one 'fabric'? Like, can there be stiffer leather sections and looser cloth sections, probably along shading regions?.

Yes. You can either make separate groups in your modeler or by way of material zones. You can also use Poser's grouping tool, but I don't recommend it ;).

Quote - Are cloth settings saved with the item when packaging? I'll be sending things to him at his college so packaging it as close to 'fresh from the rendo store' as possible will make his life easy.

So long as you set up all your settings on the clothing item before you save it as a prop all the settings are saved with it and will be there next time you load.

Quote - Every time I see a dynamic clothign item, it's very loose, hangy and plain, no doubt to take full benefit of the cloth simulation; can dynamic clothing items have uv maps or does the simulation mess up UV maps too much**?**

My dynamic clothes all have uv maps and I recommend that you create them. I also have modeled tight clothes...not all dynamic clothing has to be loose.

Quote - Lastly: are there any no-nos for making the meshes for dynamic clothing to prevent massive errors?

The only things you need to keep in mind for dynamic clothing is that it needs to be a fairly higher mesh density than conformers. If it's also a clothing item that has no rigid or soft-decorated parts, then it needs to be welded. You can use either quads or tris - both will do fine.