I'm thinking about investing in more HDD and RAM for my G74SX, but I'm very unsure about what to buy and how to replace the old HDD(s). Now I have around 750 GB storage on my G74SX (I'm writing this on another PC), will it be possible to upgrade to like 1,5 TB or something? Must the HDD be at a specific size or model to fit inside the computer? If I replace both HDDs, will I have to install the OS again?
And the RAM? Any certain models I have to use at that point?

Sorry for asking these dumb questions, I'm new into this