1. How can I earn more money? It always seems like I don't have enough.
If you just started playing, you just earn money trough quests. In the first lvls you are a bit short on money, I know, but just keep questing and you'll get enough.
2. I am currently a level 13 Human warrior. What should be my major goals and concerns at this point in the game? Are there things I'm missing out on because I'm just running around trying to do quests?
Just do anything that you like, the game isn't about getting lvl 60 and get uber gear, it's about having fun.
3. Item management. I have 4 six slot pouches and I'm still always full. Is there some crap that I should not bother carrying? I'm using my bank, but I am almost full with that too! If I'm not training to be a blacksmith do I need to save the ores that I found? WHat should I sell back, and what should be hung onto?
Never hold any gray, useless green items or anything else with no use for you. Sell them to the vendor or put them in AH.
4. Skinning. I'm up to like level 98 because I skin everything I can, but it hasn't seemed to move in a while. And when I create/make leather products, what's the use of these products other than to try to level up, and sell them? They aren't of a high enough armor level to equip. Plus, how do I know if I've made enough, or too much, or not enough of an item? I mean, I made leather kits, lots of 'em, and each one was a level up, but only to a certain point, then it turned green and didn't level up leatherworking anymore. Do I need to make everything in the list to level up?
If you are a warrior, drop skinning and leatherworking and go for Mining+Blacksmithing. That way you can create your own items. You don't have to make everything, just make the things that cost the less, but still are yellow or orange.
5. I'm always trying to get the best armor and weapons. Is there a comprehensive list somewhere that shows all my available armor & weapon options and where and when each can be found in the game?
On www.curse-gaming.com you can find AddOns. Download the AddOn called "Atlas" and the one called "Atlasloot Enhanced". Use those 2 and you can browse trough various instances and see the boss drops. Until lvl 18 you can't go instances so don't worry about "getting the best gear" yet. That's something to mind at lvl 60.