David, 10.9.3 will have 60hz. As much as I hate it, WIN8 does 60hz and even renders faster with Resolve and Adobe CC (except for Photoshop, which annoys me!).
AY, that's a 3rd party "send it in" upgrade, not a plug and play like "normal" computers. I'm sure someone will figure out a GPU upgrade as well but sending the machine out is sometimes impossible. Design pros and cons!
Simon, are you running WIN or OSX?