I bought Cats for Dummies the week before I brought my kitty home, I was so scared - and I was 52 years old! And, you're nervous because you're going to be a great kitty parent! There are a lot of books you can get or borrow from the library that will help you learn about cat behavior, this site has a lot of articles, and people will help you with your questions. And, I bet the shelter people will help you out as well.
A two year old is a young cat, not a kitten any more - there can be a lot of advantages. You'll know what size he is, the coat length, and a bit more about his personality. And, so many people only want kittens, I think there's an extra special bit of good karma for those of us who take the little bit older kitties. Mine were 4 years old when I got them (picked up as strays by Animal Control). They're both so loving in their own ways, it's hard to believe I didn't have them all their lives.
Just let him come to you in his own time. Sometimes they're a little afraid in a new home, and they don't know it's going to be their forever home. They just know they're in a new, strange place. With my boy, he hid a little bit, and I just sat in the same room and read Harry Potter out loud. Dante came out, inch by inch and checked me over, and then every day we got more and more used to each other.
You can't make a cat do anything, but they will pick up quickly that you love them, and they'll come round, especially one like this boy, who sounds like a lap kitty already. Especially if he knows you're the one who feeds him, you're the one who will play with him, and if you take really good care of his litter box so everything is nice and clean for him.
I was just thinking...and I bet you already have done this...but your mom sounds like a great person to take on a new member of your family. Maybe let her know how much you appreciate her for being willing to open your home to the new kitty (especially with Valentine's Day around the corner). Can't hurt - especially when you hit the pet store for some toys and all sorts of cat things.
Oh, check with your vet if they have a 'new kitty' check-up policy. Mine did - you could bring your kitty (or dog) in right from the shelter if you wanted, and they did a check-up, etc. The exam was free, and you only paid for any shots that were needed. I liked it as a base line to know how my kitty was when I brought her home, and also to establish a relationship with the vet. Keep all the papers the shelter will give you in a little file for your kitty, and all the papers from every check up down the road.
I really wish you the best of luck - I know you're going to be giving a lucky kitty a great home!