Is it normal when I pan/crop that I lose resolution? I tried to bring the subject's face closer tonight and it just didnt look like very good resolution. If true, then how much can I pan/crop before I start to lose noticeable quality in my resolution?
It depends on the source. What's the source? If you want to zoom in, you DO want to use Pan/Crop and NOT Track Motion. Pan/Crop will use the full resolution of the underlying image where Track Motion will only work on the current video screen.
Is this after rendering or while previewing ? If its while previewing I believe you have to be on Good - Full or Best - Full to not have the blurriness when any recompression is taking place, i.e. pan/crop.
Depends on the sharpness of the original frame, but as a general rule you're lucky to zoom in more than about 33% before the image gets softer - it's spreading less than a frame out to fill the whole frame, so some detail will always be lost.
With stills you can start at say 2400 x 1800 then zoom in a long way without losing quality.