Even after it is dry, PVA will still go sticky when it gets damp.
Not if you latex over the top of it before it gets damp don’t forget the stickiness of the PVA and the latex over the top will make a formidable coating
You can get Aquahere ™ PVA which has an active cross linking system. This means that when it dries, its set, and won’t go tacky again. it’s good for marine jobs. But I’m not yet willing to risk my life on it, and yes, it dries reasenably hard.
Or ask Steph to pass on a question, maybe? (Flatmates)
Not the same as a face-to-face, though.