Thus, if I might, let's consider one of your questions:
<Suppose my current print has fine whites, but the blacks are too grey. I could increase my exposure to make the blacks blacker, but suppose I judge that that would wash out my highlights. I changed to the next highest contrast grade. Should I change my exposure in this case?>
In the scenario envisioned by some of us, and as taught by Carson Graves, if the blacks are too grey you do not increase your exposure to make the blacks darker. As you suspected, you then reach for your filter set, and increase the contrast which will make the shadows to your liking. As Mr. Graves has taught and written, the other intermediate tones will fall into place. Since your filters are speed matched for the highlights, your exposure for the highlights will be correct. If for some reason the highlights are NOT correctly exposed, then small changes in the highlight exposure should be considered. In the scenario we espouse, always expose first for the most important highlights, then examine the print. Modify the contrast based upon the shadows....too black, decrease the contrast grade; too grey, increase the contrast grade. The nice thing about VC papers is that the contrast grades might be almost infinitely variable ( depending upon your filters, your paper, your developer ) by using small changes in the settings of your filters. Thus, you might be able to dial in a filter grade of 2 3/4 if 2 1/4 isn't to your liking and the shadows aren't quite right to your eyes. As needed, modify the exposure slighlty so that the highlights in each print are the same, or very similar to the highlights in your test strip, or first print. Those of us who like to experiment with graded paper can also try to find some intermediate grades, but we must use different developing times, or developers, or combinations of both ( ! ) in order to more finally tune the contrast we seek. Frankly, as I write about the subject, using VC paper appears to be much easier!
I sincerely hope that we all have been of a little help to you, and I wish you much success in your endeavors.