There are several different species of fungi living in caves and most tend to grow quite fast. there is of course other types of cave plants like moss and cave grass. These are considered the vegetables of the Dwarves. Underground lakes and rivers provide fish and seaweed and lets not forget the tasty mountain goats provide milk and meat. Centuries ago the Dwarves have figured out a combination of mushrooms and mountain herbs called Spoiler that when ingested allows them to breath thinner air so smoke in the homes doesn't bother them nearly as much. combined with their short height, much of the smoke is seen overhead anyway. The forges are always in rooms that have very high ceilings. Usually a large central cavern that have heights of the middle of the mountain they have inhabited and always have a steady stream of lava in the form of a river and usually a waterfall to help with the smelting process. This leads many outsiders to believe the mountain is a volcano ready to erupt at any moment so people tend to stay away.
If you were to ask a Dwarf about Stonespore Ale, he would tell you that particular concoction protects the drinker from extreme heat allowing them to live quite comfortably around lava and huge bonfires. And we all know just how much Dwarves are a lush on a slow day. One does not want to get into a drinking contest on any day of the week with a Dwarf.
When it comes to the economics, things get a little tricky. Gold is of course the main currency, jewels are just a higher value of the same currency. However because of the amount that is mined everyday thru out the mountains they mine, everything has a very high price. When trading with outsiders Dwarves are well known in trading their wares for other things such as cow milk and meat, potatoes, carrots and other foods that cant be grown or raised in the mountains as these things are considered a delicacy. If the merchants knew just how much Dwarves tend to have in gold coins they would likely charge overwhelmingly high prices and still the Dwarves would have no problems affording it all.
... Or at least, so they say.
I hope this answers some of those life questions. lol