Should run that and most other modern titles very well. Dont need 16gb of memory, get 8 gigs of faster memory. And make sure your PSU isnt garbage or else youll have issues with that card, and could ultimately damage it if it isnt a quality PSU.
It will run it no problems. Do note that a 2GB 560ti (like the one you have listed) is not better for games at resolutions at or under 1900x1200, and you are better off getting a 1GB 560ti (like the one in the link below).
It is completely dependent on your resolution. GTA IV is one of the most appallingly coded games in history and as such runs run like a legless dog on a leash regardless of the horsepower behind it. If you only have a single monitor at 1920x1080 it should run OK but don't expect anything special.