Apple pollination, management & pruning

When I bought my house, I inherited a yellow transparent apple tree which had been pruned and tended over the years, for which I am extremely grateful, since it's pretty old and could easily have become unmanageable if past owners had neglected it.

I've maintained it as best I could - and despite the ministrations of many caterpillars, the appetites of the birds



and the cack-handed interventions of a tenant who lopped off all those unsightly fruit-bearing branches while I was in Italy, it has flourished and fruited reliably.



Every spring I climb up into the tree to nab the water shoots, and when I can organize myself I give it some dormant spray in the spring as well, but that's about all I do.

Apple Tree Care
Things I've learned this year about helping it further include:

understanding pollination - because most apple trees must be pollinated with another variety (or must they..?) I guess I owe the fruiting health of mine to that of the neighbours' trees; not sure of the varieties but there must be something compatible nearby. My mason bee boxes have provided me with some good little vehicles for neighbourhood pollination.

grafting - my brother's experiments in grafting have given him some interesting variation, and I suppose makes a tree self-pollinating.
don't mess with nature - fruit trees need to pay attention to the season, so no pruning or fertilizing in the late summer or fall, as these will cause it to keep growing instead of hardening-off to protect itself from cold weather.
regular watering - fruit trees need an inch of water a week, same as the grass, and do better with one weekly deep watering than frequent sprinkling.
root space - grass and fruit trees are not, despite human interventions, good bedfellows, since grass wants to crowd everything else out. A dense root structure in your grass means less water gets through for the tree, so you should have an ungrassed region around the tree's base to let water through. Not sure how to approach this since the tree is mature now and its roots must have pretty wide reach. Perhaps the easiest thing to do would be to mark out a big circle under the canopy, bring in some chickens to bare and fertilize the soil, and go from there with the mulching, planting something low-growing, shade-loving and food-producing that will let the water through. Now I just need to borrow some chickens...
feeding - like all plants the tree needs nourishment, though is more resilient than most garden plants. You can apply perhaps some form of (non chemical!) fertilizer in the spring (but not later). Organic mulches and compost are recommended. Same problem as watering in the mature tree in that you might not know where the roots have spread. I've heard that spraying the tree with compost tea will protect it from insects and nourish it as well.
summer pruning - I heard that pruning the water shoots while the tree is in leaf can help it focus efforts on growing nice fat fruit, so I did that this year. I'm not sure the result is any better than in previous years, but I did get some nice leaves for my compost -- although some of them came with freeloaders:

Like most things to do with gardening you get wildly conflicting advice everywhere. Although I was told that summer pruning would enhance fruit development and also bring more light into the ripening fruit in the tree; I also read that removing these shoots removes a nutrient source for the tree ("decreasing canopy photosynthetic efficiency and carbohydrate production") so not everyone recommends it as you're then diverting the tree to replace that lost food. We'll see what happens.
thinning - hard but necessary, removing excess nascent fruit in order to get better, bigger apples

Pruning
I've been looking up information on pruning in general as it's a complicated business, and my property also includes a neglected plum tree that has not been maintained, no longer produces well and is almost impossible to harvest because of its position and height. Here are a few sources I checked out:
Cognition (now called Canadian Organic Grower) had a helpful article from which I learned the useful issues around renovation vs. maintenance pruning.
Fruitwise has some video tutorials (and a website on heritage English apples) which give great advice on the basics of pruning including choosing the right tools for the job and proper secateur technique.
Oregon State University Extension has an article on restoring a neglected apple tree.
Rona.ca has one with notes about pruning issues specific to tree types, including plums.
Wikipedia has a nicely illustrated article that lays out what to do to trees at different ages.