My understanding and observation with most softwoods is that within the range of about 6 to about 40 growth rings per inch most strength characteristics revolve around the percentage of latewood. The greater the proportion of hard, dark rings, the denser and stronger the wood. This is loosely what the grading rules are looking for when they seperate dense from common.

Can't say much on the pitch accumulation other than fatwood will outlast stone. Pitch is usually an injury response. Those cells can be some of the last to shut down, under the right conditions they can keep producing resin for months after the tree is felled. Not pitch bleeding, resin production, never say die.

The earlywood, lighter ring is put on in about a month's time, around here on EWP it does that burst around June. You can almost watch them plump and shoot up. The darker latewood ring is laid down over the rest of the growing season.

My science on this is weak, but what I think you are seeing in spring Derek is starch converting to sugar, which pulls bound water out of the walls into the lumens and causes flow. I don't mind being corrected there.

To keep edging out on that limb, that has to be part of how softwoods survive embolism. Somehow using that sugar pull to re-establish their water column. Usually the freeze induced embolism is what causes the range limit for species as you trek north. Finally getting far enough where the hardwoods can't survive, to where they laugh at the cold, keep their needles, and reboot themselves after being frozen solid. Now that's a tree.