Yes, you can use this to access any blend file, and convert the contents of them into assets.

100% YES

Use the "Create materials" options, choose what shader you want to use (Uber, Organic or Plastic), choose a folder with any amount of textures in (It'll just batch through them all automatically) and then hit OKAY. 

All your texture sets will be converted into materials before your eyes

Yup

Just use the "Create worlds" option, and point it at a directory with HDRIs in... Worlds before your eyes with our custom world shader.

Nope... The tool is not meant to help creators pack their own content.

True-Assets is a tool for artists to gather all their existing blends, texture libraries and HDRI libraries, and put them into Blender with a couple of clicks.

We do not advise using True-Assets to make a library that you intent to sell as it will be packed into our custom paths

Yes! 

Just use the "create assets from directory" option, and choose what kind of assets you want to make:

• objects
• Materials
• Worlds
• NodeGroups

It will run through all the files and put what you chose, into your asset browser automatically.