Generaly speaking you can sell anything that isn't soulbound at the AH, including mats. So the answer to your fist question is yes.
As for the price here's were it gets complicated. AH prices very by server so I could tell you that a stack of 10 light leather on Blackhand sells for 50 silver but unless you're on blackhand that price is completely useless to you.
You need to actually meander over to the AH (if you can not locate one in the captial city you're in ask a guard) and type "light leather" in the search blank. And yes you need to spell light and leather correctly AND include the silly space for it to work.
Hopefully at this point your AH window shows a bunch of light leather. You need to scroll through and find the cheapest price for the amount of light leather you want to sell. Then post your leather for 5% less ;) Ie. You see JoeBob is selling 10 light leather for 50 silver Buy out, you would be wise to post your's at 45 silver buy out. Yes, 60% of WoW players are cheap I will always go for the lowest price available.
Hope this was helpful.