I'm still using underwear from David 3 from a vendor no longer selling and various items from Rendo in my promos. As long as the promos look good, they don't care. Really? Weird. Are you allowed to list it in the credits?

You don't list items not in the store or not available, but you are free to use them in promos.

Can't speak to percieved "strict TOS", but except for not allowing to make addons for things that aren't sold in the store (since in the past those things disappeared from sale, leaving orphaned items) none of what you typed is correct. The strict TOS I am referring to is for the forums, and not the store. Oh, I also forgot that unlike Rendo and RDNA, there is a no nudity rule on DAZ. This has been a problem for me since I like to know what color of nipples the gals with fantasy skins have >_>

Actually you can link to a gallery that has settings for mature flags and add that into your product description.

_ and the product has to be exclusive or they'll remove it from sale,_ That was what I used to assume, until I noticed products sold both at DAZ and here, and finally due to what the official publishing faq says: http://docs.daz3d.com/doku.php/public/publishing/faq/percentage_of_sales/start

No, they'll remove them. One product was offered here after being offered on DAZ last month, DAZ removed it from their store.

The royalty rates for non-exclusive agreements are much lower, but decided on a product by product basis.

I believe that only applies to software and some utilities, not content for figures. But it has to be negotiated when the product is accepted, not later.

The FAQ also says that metadata has to be created by users, and it jives with complaints I've heard from vendors in the past 3 years. http://docs.daz3d.com/doku.php/public/software/dazstudio/4/userguide/creating_content/packaging/tutorials/adding_metadata/start Tools to create metadata for new products are provided with DAZ Studio 4. In the future, this may become automated as part of QA, but for now, this needs to be done by content creators for new products.

No, it's done by QA when they make the installers. That's the "automated as part of QA" you just quoted. I've never had to make metadata for my products in the last 4-5 years since the introduction of DS4.