Take the slime downstairs

I assume you mean a Bolt of Mass Destruction?

In which case, in my experience yes, they do destroy walls - first time I ever found the bolt I got a pair and tried one out a short time later to see what they did, I completely took out one end of the "archery practice" shaped room I was in (although, not the targets on the walls, so they clearly don't destroy everything).

Ingots have limited uses outside of forging. They can be:

• Ground with an Elven Grinder, to make ingredients for potions,
• Sold to Brax,
• Transformed into lutefisk with the Hodaric cube.

If you chose to transform then, you should rather make something like bolt from them, in order to obtain more lutefisk from one ingot.

Edit: If you want to sell them, you should before try to craft them into something more valuable, depending on the ingot type:

• Plastic into plastic ring,
• Copper and tin should be made into bronze then a dagger or gladius, if you don't have enough tin, make a cooper ring,
• With iron, try to make steel then a steel cuirass or even a full plate armor if you have enough,
• With aluminum, also try to make a cuirass,
• Zinc, brass, silver, gold, electrum and platinum are good sold directly.

There may be better deal with cross-metal crafting, but this is what I found for direct metal crafting.