Hello Paul and thanks for this interesting story.
Yes fruit benefits from thinning, no doubt about it, even gooseberries. Fruit is sweeter as well as plants cropping more regularly.
The difficulty is to thin one’s fruit enough, you need to imagine them full size when thinning and late June to mid July is best time for apples. It sounds like you know that now, well done for working it out.
As for the bark damage, it does sound like canker, but of so the branches often die within perhaps a year, and are best cut off below the damaged area. Easier said than done if the trunk has canker.
Happy harvesting this year!
