None are any good, because after a few weeks or so, all the chests reset and the enemies respawn. You'll lose anything you stored, and you'll have to clear the cave again. Better to obtain one of the game's buyable houses.
By making potions.
Look in kitchens and alchemy shops everywhere.
48 hours is the time when you are out of the vicinity of the chest.
This type of weapon is usually a random drop. Or you can find them randomly for sale at weapons vendors. Alternately, you can create your own at an enchanter table.
At a very high level there is a possibility. By then you will have enough money to buy it. So you might as well learn how to make it yourself.
yes, If you are involved with that guild.
Sawn log. Nails. Refined moonstone. Iron ingot. Grand soul gem (with grand soul). Gold ingot. Just need one of each.
You can buy one from the priest in the temple in Riften. Other than that, you can find them in dungeons or chests on your journeys. Some draugr will carry them as well.
You don't "make" the alchemy labs, in the normal sence. You can either use the ones in the alchemy shops (where you buy supplies in almost any town) or it's something you can buy as an addition for any house - other than Whiterun - from the same person you bought the house from.
Yes, if you have the Hearthfire add-on. The enchanting room, or the alchemy room, is traded in for a children's bedroom. Go speak with the steward.
You can NOT find spriggan sap by killing spriggans contrary to Primas Official Game Guide. However, you can find spriggan sap on Spriggan Matrons. You can also obtain spriggan sap by traveling around to various alchemy shops around Skyrim and buying it there.
The Skyrim helmet is called an Iron Helmet in the game.Enchanted and unenchanted variants begin to appear throughout Skyrim at level 1. These locations include:Blacksmiths and General Goods Merchants.Found as random loot in chests or as a world item.Worn by Bandits.Can be found just before the Bear encounter during Unbound, next to a cart after crossing a small stream.You can also craft it with 2 Leather Strips and 3 Iron Ingots.Source: The Elder Scrolls Wiki page "Iron Helmet (Skyrim)".