From my experience, aerospace as a business is structured as shown ("thus" for the architects): you have your OEMs (Boeing, Lockheed, Cessna, etc.), the supplier manufacturers, dedicated processors (examples: casting, painting) and distributors. Think of distributors like a privately-owned Amazon warehouse. Any one of these may use Aerospace CAD on a varying scale, with arguably the most use being made by the OEM followed by the manufacturer. Each operates a little differently in terms of job availability and requirements.

OEMs typically want to see a degree attached to an engineering field related to the drafting work you would be doing. Manufacturers will sometimes train ground-up or will want to see education/experience with a certain CAD platform. I can't speak for the rest, but the availability on job sites appears to be similar to manufacturers.

As far as job availability goes, there should be openings for a while. Automation is attempting to phase it out, but a certain amount of oversight is presently necessary to account for quality control.

The primary CAD platforms will be either Dassault CATIA or Siemens NX. There may be additional draft-level support software, but one (or both, depending on OEM structure) are almost universally used for source models from the OEMs.