Knitting is quite confusing at first. But it get easier over time, don't worry
Okay for your first question:
Crochet is a little bit like knitting, meaning it's all about string and making stuff. But crochet uses only one hook and the fabric is quite tight and not-flowy. Knitting uses two needles, one holding loops and one making new loops on it. Knitting has more flow than crochet, which is why I perfer it.
Yarn is labled in many different ways (they still confuse me ^_^;
. There is the brand of the yarn, they type of yarn (wool, cotton, ext.), how to wash it, the gauge, exetera exetera. For now, you can just pay attentian to what type of yarn it is
Yes, there are different kinds of needles, in sizes and materials.
Wood Needles: these come in many different flavors, including rosewood, mahogany, and bamboo. These are good for beginiers (I think) because they're nice and stiky, so you don't have to worry about dropping stithes. I like them, they were the first needles I ever bought.
Meatal Needles: I have just recently fallen in love with these needles. They're slippery so I can knit faster, and they come in lots of pretty colors. But I think they're better for more experianced kniters, because they made me drop A LOT of stiches.
Plastic Needles: these are kinda middle ground. They're not too sticky and not too slippery. They're also very cheap and flimsy, so don't hang from a clif with them.
The number of the needle depends how thick or thin it is. For meteric and US sizing the larger the number the thicker the needle. But for UK the larger the number the smaller the needle.
I hope that answerd all of your questions. Just ask if you have any more, the ladies (and select few guys) are very nice