A curse and the demons are two different things. But the short-answer is no. Even people in a state of grace can be possessed, though it is rare. A curse doesn't really have an effect on someone living a sacramental life, but it can *if God allows it*.

Curses make it certainly easier for the demons to possess, or obsess someone or something. I know of a particular case right now of a friend who's father has a generational curse by Freemasons on his family and is dealing with possible possession and oppression, he has already seen multiple exorcists about it. His issue is that he is not a practicing Catholic in a state of grace, but wants to be. He is baptized however. Wonder if we're talking about the same person perhaps.

If someone is baptized, that doesn't ipso facto mean they're in a state of grace. They can lose the state of grace and innocence by simply committing one mortal sin, and in today's world it's easier than it ever has been. When you are baptized, you are put in a state of grace immediately, but as I just stated, it can be lost by one mortal sin, and one mortal sin is enough of a gateway to become possessed, baptized or not if God allows it. It's ultimately up to God whether someone becomes possessed.

You can listen to all Fr. Ripperger's videos on Sensus Fidelium and he explains all this in detail.

NO priests do not get ordained exorcist especially either. Exorcist is one of the minor orders that Catholic priests are ordained.