I'm sorry you're having problems. I'm right there with you if it helps? It's nice to be able to compare notes... so many different sets of instruction!
I would imagine the use of adhesives might depend on the type used. Mine are Visco-Gel.
You'll probably find your gums will toughen up faster leaving the denture out at night. Mine did just after a couple nights.
Look really closely at the scratches on your dentures. I thought I had a spot in the finish, but it turned out to be just a little excess liner on the outside of a front tooth. What a relief that was! I sure felt silly when the assistant showed me what it was, though.
I was assured that the acrylic used in the dentures is pretty tough stuff. Abrasives (toothpaste) are to be avoided, but a good brushing with a soft brush is fine. The denture brush I was given seems much harder than the toothbrush I actually use.
Good luck at your appointment tomorrow. I hope things feel better afterwards.