Scanned object CAD format? 3D Printing?

[DonRotolo]

For a non-robotics (and non-commercial) project, I have an object that I intend to have 3D scanned and converted into a CAD file of some type, ending with the object being 3D printed somehow.

A company offers fairly low-cost scanning services. I figure I can get the object scanned, import it into Autodesk Inventor, clean the scan up* and send it out to get printed.

My question is into which file format the object should be scanned. A 3D mesh model is less costly than an IGES or STEP file, but I am not sure of the difference between the two, especially in terms of my ability to import it into Inventor and then work with the file to clean up surface imperfections.

Then I have questions about 3D printing: This is a prototype, so it needs to be inexpensive as a proof of concept, but eventually these may actually be produced (Just a dozen or two per year). Ideally these should be chrome-plated plastic (I assume vacuum vapor deposition for "plating", other ideas?).
Any thoughts on the best method/material for the prototype (low cost), and then for production (can be 'plated')?

*I have seen the results of raw scans, and they always need cleaning, plus the object is not a perfect example with some surface imperfections already.

The object is like a radio trim plate, about 7-1/2 x 2-1/2 x 1/4" thick, wall thickness generally 1/16" to 1/8" with no fine details, and mostly air as it is a frame, not a solid rectangle...if that helps.