I don't know for sure, but I think semi-pro to pro is compulsory when being promoted into league 2, so clubs probably do in the game if getting that promotion
yes they do, I remember seeing clubs go from amateur to pro status when leaving my San Marino DB on a holiday test.
and I'm fairly sure the can go the other way aswell as I think I remember seeing one of those holiday saves to the year 2100 or so end up with a semi pro everton in the BSN.
I'm in 2020 in my save, and it looks as though any team promoted to League Two goes Professional, but teams relegated into the Skrill Premier retain their Professional status. The Skrill North & South contain a few Professional clubs, too.