Hello Don
1, Yes for video astronomy type applications, when using the ICX825 our hot pixel algorithm is better than using dark frames.
2, Ahh that depends. The major differences between the two cameras are read speed and cooling. The infinity will have a higher read noise due to its faster download speed and more thermal current due to not being cooled. In exposures of seconds the noise associated with thermal signal is irrelevant so will not differentiate the cameras. The read noise will be and electron or two higher in the infinity so may effect the quality in the fainter parts of an image. It will be a relatively minor effect. For exposures of minutes the 414 should return a better image due to its cooling.
3, The infinity is based on a high quality microscopy camera. This uses 12V as it offers the ability to use significantly less powerful, noisy, charge pumps to generate the higher voltages the cameras needs.
Best
Steve