Maximum fps@resolution needed in particle tracking?

Firstly, what is the ideal digital resolution of frames for accurate particle positioning? Literature reports suggest roughly 1024×768, but why?

Secondly, what is the maximum fps of the digital camera to allow the widest application? 500fps showed up in literature in order to track the particles in low viscosity environment, but why 500fps quantitatively?

Possible candidates (around 1024×758@500fps):