Jeff, you're much more ambitious than I. I think its best to focus on a single variety for at least 5 to 10 years and only work with a couple of spawns within that variety each year. With this approach, you learn which pairings provide the best results and you learn how to cull for fish that develop well over the long term. I am just now graduating from kohaku to sanke, so I can't comment on any of your selection queries.
It is interesting that when you hear people on Koi Bito talk about pairing koi, they always seem to be intent on finding a good out-cross. They want to cross one "line" (use the word loosely) of a variety to another line, or even cross one variety to a different variety. This is contrary to most other types of fish breeding where they in-breed until some weakness in the line becomes apparent and it is necessary to out-cross to renew vigor. In-breeding is the best way to increase the percentage of offspring with the parents' desirable characteristics. The more genetically differentiated the parents are, the more variability there will be in the offspring. It is, after all, a numbers game.
For us hobby breeders, the out-crossing is often an artifact of our collection of adults. We acquire fish because we like them, not because we plan to use them as breeders some day. I am trying to move to the next level and purchased a group of tosai from a "line" that had been in-bred for 20 years. I wish/hope they are all siblings, but the cost to hunt down a group of known siblings was more than I could afford. The ideal would have been to acquire known siblings sansi, but that was way out of my reach. These fish have grown well since last June and may spawn this year. When mature, these fish and their offspring will be my broodstock for the next decade or so.
There's quite a bit of info out there on the science of spawning and larval rearing. There is almost no information on pairing and culling. However, the lack of info on pairing and culling may simply be because it is art instead of science. You find a good pair using instinct and trial-and-error. You cull based on your artistic vision and you may need to use different culling criteria for different "lines" within a variety, or even for different pairings.
-steveh opk ins