im not sure how you extend your waranty but with dell they sent me an email and a letter in the mail. From what i read with macbooks you're allowed to change the hardrive and ram and with macbook pros you're only allowed to change the ram, so you should be fine.
I would also recommend that extend your apple care, it should cost around 250 or less if you're a student or if you can get a student to buy it for you lol
One repair and the apple care pretty much paid for it self, my macbook had a messed up trackpad button when i bought it (was a refurb) apple fixed it right away and according to the receipt it cost them 270 bucks.
Laptops break and fail easier than desktops, why take a change and get stuck paying alot of money or possibly having to buy a new laptop or possibly having to live with a laptop thats missing a keyboard key or something.