The Tavern

I'm a HOPr at XL 15. I was holding my own on dungeon level 17 until I found out that wizards can banish me. Am I as good as dead or do I have a chance of escaping?

It won't be easy but yes, you probably have a decent chance at escaping. This depends a lot on your consumables, too, especially !speed and /hasting.

I found a gate out in 2 minutes! Now I am on fire from liquid flame. What resists help with that?

Either rF or special sticky flame resistance (from mottled dragon armour (but the fire will be out before you put the armour on anyway)).

Fire resistance helps with resisting fire.
A cloak of preservation or an amulet of conservation will help protect your scrolls (though not infallibly so).
Mottled dragon armor will make you immune to sticky flame.
Also, spending a turn in water will put out the flames.

I survived the abyss!