Noob question [10.11.6] can I update App Store (security patches)?

Hello,

Sorry for the noob question but rather than turning my mackintosh into a brick I thought id ask the question.

Is it possible to run the AppStore and update as it found a few files, 1 begin a security patch.

Will I be okay to do this?

Also my Nvidia card is running fine but says 0mb..... is this normal?

Spec

MSI Gaming z97 board
i7 4790k 4ghz
32gb DDR3 2400
GTX 650TI 2gb

Same, I updated iTunes but didn't do the Security Patch in case something goes wrong, especially as I don't have a backup, I don't even know how to do one!

Got help with the gfx issue, but unsure if I can update my mac osx... like latest patch etc