A “project” saves the model as a “.3MF” file. (3MF = 3D Manufacturing Format)
A “.STL” is just a mesh of the model. A “.3MF” file has the mesh but supports multi-material. It can contain meshes and tag them to a material.
But a .3mf file can also tag machine info, print settings, material specifics, etc.
The .3mf file is actually a .zip file. You can use any zip extractor tool to take a peek inside the file. The data in the file is regular text.
I saved a “project”, made a copy of the project file into a temp folder, and unzipped it so I could explore the contents. Turns out it names the materials. It records the print settings (pretty much everything you can tweak in the “custom” settings panel).
Print settings should be retained (when I open the file it does remember my print settings).
But be aware that just because a .3mf file can have this info doesn’t mean it will have the print settings info. You can tell a CAD program to save the model in .3mf format (if it supports that format) and you’ll get a .3mf file but it wont have any print settings because the CAD program doesn’t have anyplace to define those settings. In other words you’ll need to make sure you don’t mix .3mf files created by Cura with .3mf files created by something else. (I specifically add “proj” into my project file names when I save them from Cura.)
I don’t see anything in there that records build-plate orientation. The part I used to test hadn’t been manipulated on the build plate (I didn’t scale it, rotate it, etc.) so not sure if any of that would have made it into the .3mf file if I had. Parts do have a cartesian coordinate system (e.g. since it’s text data providing x,y,z coordinates for each point … a part is going to open with the part coordinate system matching the build plate coordinate system.)