The recruiter will probably get the full name, position and true email address of the hiring manager.

Plus, if the charade goes a few more emails, more details about the job.

I don't think they pose as applicants as much as they use the contact method (usually email) to solicit their services, even sometimes ignoring when the hiring company specifically says "please no recruiters." If they are posing, it would be pretty easy as well, as they could send in resumes & CV's of job seekers they represent.

Recruiters also pose as companies posting 'jobs', and from what I've seen when looking for gigs it's likely they solicit in the other direction as well. How low they sink, who knows.

The recruiter may be representing a "stable" of clients (programmers) looking for jobs. The recruiter would want to talk to the hiring manager to sell them on (any of) their clients (shotgun approach), without figuring out which resumes might actually be a good fit.

Alternatively, the recruiter might want more details from the hiring manager about the open position, so they could hunt for applicants to bring back to the hiring manager.

a recruiter will get all their information including direct contact email when they respond to the fake qualified resume the recruiter submitted, then the recruiter harasses the hiring manager(s) directly on linkedin and email, or sells that information to their applicants, or other recruiters.

Or they bait and switch, saying that person is no longer available and give a second resume, knowing they have full attention of whoever is hiring. Or they would find out their phone numbers and harass them with endless calls.