Publius
Yes, he can -- and should.
?
No she has to be under 18 and then she is jail bate. But 19 she is old enough to make a choice. As long as it is not rape? your safe.
?
No, you are both adults and as long as there is no
coercion. In some states you can get married.
Not recommended though.
Artemisc
The age difference doesn't matter. Sex with relations is determined at the state level.
Pacha
No, not if it's concentual..