2) Currency/Worth of items. It's cool being new to a game where you're still learning, but this is an area that is a must. I'm using certain guides to see what items they're using, etc... but knowing what makes an item worth something is necessary for trading and obviously improving your char. The obvious ones are max life and resist, but it seems there's a lot to learn in this area....
I've played PoE on and off since beta and I still have a tough time valuing items, and it changes month to month with flavor of the month and patch changes. The whole game is so damn complex that after a 6 month break it's fairly daunting to get caught up.