Spoiler
About your pickaxes burning. A RoI(it's blessed isn't it?) only protects your worn equipment, not the ones in your backpack. To protect non-worn equipment you need fireproof blankets. I'm not sure if you were clear with this one. Also, you've been in the darkforge. I hope you're not using the crown of science for fire immunity because it makes you doomed which is never, ever a good thing. In fact it's much worse than fire immunity. Doomed also makes all of your stuff burn way faster than normal. Usually when I go to the ToEF I'm blessed(crowned), lucky and fate smiles without cursed/doomed and I don't get one fireproof blanket burned during the entire trip. You can get sufficient fire resistance for ToEF's background heat with a blessed RoFR(fire resistance) and elemental gauntlets(if you've also eaten some fire thingy corpse). Rings don't get burnt under gauntlets and artifact gauntlets don't get burnt. Unfortunately the pyramid is closed for you, as in the pyramid you can find a climbing set and a pickaxe(as well as thieves picks). They're on the far left of the first level, behind some secret doors.

You should be in good standing with your god. You can pray on the top level of the ToEF for a pickaxe. That's good but there's also a downside: when fighting the ACW or other creatures don't rely on your god for healing as he might just decide to give you a pickaxe instead:)

BTW, on some level in the CoC you have already passed the water temple. It should be easy to find as you have only searched half of that level. Also when entering the level you get a message saying something about water constantly dripping on that level(you might just get it the first time, turn on verbose_level_messages=true in the variables to get it again). You might want to get the water orb before going to the ToEF, it gives +10 Wi which makes your wand of digging shoot farther(correct me if I'm wrong, I think it's Wi dependent) and helps avoid confusion.

If this is your first time in the ToEF I think you could need a few pointers on how to have better chances in there. In another thread you said you have a human fighter. I guess you got healing in the beginning instead of herbalism. That's fine but you still might want to gather some spenseweed from somewhere. It'll be cursed but that's no problem, just uncurse it. You need ways of healing because you can't teleport away in the temples, and if you use a 2-hander you will have low DV and will get hit a lot(that also means a lot of corruption...). Also if you're a human fighter it means that you lack alertness, which means you will get hit by the ACW's powerful energy ray. It's been a while but IIRC it easily deals over a hundred damage. So be careful and have some way of healing with you.

Last but not least, there's one way of killing big ugly powerful monsters that's much easier and faster than just bashing them in melee(getting hit a lot and corrupted) or hitting them with bolt spells which they usually bounce off anyway. Slaying ammo. You have probably found some dragon slaying ammo, bless it and shoot the ancient chaos wyrm. It'll die a lot easier. You could also use demon slaying ammo for the fire demons. I think humanoid slaying ammo also works for most demons. If you haven't been training missile weapon skills, well, maybe in your next game you will:)

Spoiler

1.- the guardian/bridge building. You mentioned that you have the 'mana battery' corruption, so that makes it harder. You can freeze the water, if you stand next to it, and shoot a frost bolt in it's direction. Wands of Cold do the same thing, so you'll either have to learn Frost Bolt, or wrench the final charge of 3 wands (remember - you must be next to the square you want to freeze, and ice can lift only 2000s of you stuff)
2. Yes, they do give more xps.
3. He gives 2 quests (both are very lawfull... kill the druid and kill the Dwarven elder ;P ). He gives 2 artefacts - both are veeery nice but corrupt as hell. Don't touch 'em. So you can kill him, or leave him alone (that second option is what I prefer)
4. Crown of Science - you know the down stairway in DF? In the middle of the corridor (once filled with golems) there is a fake wall (in a 'former golem place').
5. Corruptions - 18 of them, to R but you'll never have more then Q. The "R" corruption kills you (or rather turns your char into a purple, mindless 'j').
6. Vaults can be everywhere. They are generated randomly - you can finish the game without seeing any, or there could be one on every non-special level.

Spoiler

One very effective way is that second druid quest you mentioned. Once you're level 30, go talk to the druid in Terinyo. He'll tell you about a good and noble creature in the forest who needs your help. That creature is a white unicorn, and if you help it, it will be able to cleanse all your corruption once.

Another way is potions of cure corruption - bless them before you drink them, and if you have poison hands, wear thick gauntlets. If you give the druid the corpse of an orb guardian, he will give you a blessed !PoCC.

Finally, there are scrolls of chaos resistance, as you mentioned (again, they should be blessed before use). There are five "guaranteed" sources of SoCR, but not all will be available to you.

• If you save Khelavaster's life, he'll give you a nice reward including six blessed SoCR. Sadly, I'm guessing that you allowed him to die.
  
• The Dwarven Mystic (who lives inside the secret room in Dwarftown) will sometimes give neutral characters four blessed SoCR.
  
• If you spend a long time in the library studying spellbooks, then talk to the Ghost Librarian, he may give you a weird tome to deliver to the Mad Minstrel, who will reward you with five cursed SoCR.
  
• The statues in the Bug Temple contain 3 cursed SoCR, but be warned that it's VERY dangerous.
  
• Finally, the secret room in the HMV contains one cursed SoCR.
  

SoCR can also turn up randomly and can be wished for.

Spoiler
On the bottom level there are 4 minotaur mages surrounding the minotaur emperor who is in the middle. They are in the shape of an X. The minotaur emperor carries the Axe of the Minotaur Emperor, which is very powerful but weighs 1200s. He also leaves other items, like a PoGA or PoCC. BTW, if he steps into a corruption trap he gets healed, so he is pretty chaotic. Maybe you could get a PoCC if you took his corpse(I think it's guaranteed) to the druid in Terinyo?