Can my son re-enlist in the Navy after receiving a RE-3J discharge code?

That is a question for a recruiter, not a lawyer.

You can be discharged for "commission of a serious offense" even without a conviction. But no lawyer can say what happened without reviewing your...

You will have a warrant issued for your arrest.

Can i join US military, i am not a US citizen nor i have Greencard?

This is a question for a recruiter, not a lawyer.

A relationship? Yes. Sex or sexting? No.

You would have to ask the applicant. The DD 214 doesn't say either way.

Looking to find an estimate on my case?

AVVO rules prohibit us from contacting you directly. You will need to reach out to lawyers and have them review your case and give you a cost...

What would happen if federal background investigators suspected you of lying, beyond your clearance being denied?

Lying to investigators is a serious crime. Don't speak to them without retaining an attorney first.

There is no time limit. Theoretically this can go on until you ETA. And yes it stops you from getting promoted or from a PCS.

This is a site for lawyers to answer general legal questions. That is the "help" that we provide. You need to retain a lawyer in your home state...