There is very good information on the VASST site: see DSE's book on HDV where setting for various HDV cameras are discussed and results illustrated. Generally higher gain means more noise (because if your CCD receives insufficient photons to adequately fill each pixel well, you apply gain to boost the signal which also boosts the thermal signal noise sitting down there at the bottom of the well). So most else follows. In a concert scenario you're may be wanting to grab as many photons as possible, so open the aperture and use the lowest shutter speed appropriate (1/60 sec for 60i). In fact unless you're wanting to reduce motion blur there are few reasons to use higher shutter speeds and you could even try lower. Don't use too much sharpening and otherwise generally the default settings work well. With the Z1 you can add some black stretch. If you have a lot of light, don't close down the aperture too much (f/5.6 is a nice working aperture) because you start to degrade definition by diffraction.
As said above, the bigger the pixels the greater the number of photons that can fall in the well, but for a given size of chip bigger pixels mean lower resolution. But because pixels aren't jammed together there are means to gather photons that otherwise would fall on dead areas of the CCD, in which case the pixel gives better S/N than the strict comparison of pixel areas would suggest.

This is very quick & rough, but hopefully of some help.