Can I have some help in a desktop computer upgrade with RAM and video card?

I have a Dell that is about 4 years old, and I want to get a 27 inch monitor for it for high definition picture editing and video watching (Netflix, etc.) I have no interest in gaming. The problem is that the video capabilities do not support it. I’d like to avoid getting a new computer if possible.

Specs:
64 bit Windows 7, i5–2500 CPU at 3.10 ghz with 8 gigs of RAM

It looks like the current monitor is plugged into the mother board. There appears to be a couple of open slots in the back, although I haven’t opened it up yet. Truth be told, I’m not sure where to look. I’m assuming there is a PCI slot, but I’m not sure what a PCI slot looks like.

So my questions:
1) Can I simply get a video card and plug it into the current machine? Or is it more complicated than that?

2) With an i5 processor, can I get 8 more gigs of RAM to make picture rendering faster?