As was noted in another post I do not recommend the post-fixer alkaline bath for Pyrocat-HD. The alkaline after-bath serves no useful function in my opinion as it results primarily in general fog, same as b+f stain that does nothing to enhance the printing qualities of a negative, IMHO.
About fixers, I use the alkaline TF-3 fixer described in Anchell and Troop's The Film Developing Cookbook. However, I would not hesitate to use an acid fixer with Pyrocat-HD if that was all I had available. There might be a very slight decrease in the amount of image stain but not enough to be of any consequence in my estimation.
As for the impact of the color of the stain on VC papers I wish I could be of more help. However, the truth of the matter is that I am printing exclusively these days with alternative processes and have not made an enlarged silver print in several years. In fact, I recently discarded my old 5X7 enlarger to make more room in my workspace for other things and don't feel even the slightest sense of loss.
So if you get too confused about stain and VC papers, just get rid of your projection equipment and print with AZO, which is about the best silver paper ever made, if not the best, or switch to one of the alternative processes!!!