You do not need to be above the tree to prune. You could have a branch that is 10' tall and cut it at 4'. You certainly wouldn't need to get on a ladder to make the 4' cut just because the branch is 10'. All the trees you mention except for the cherry, which you will probably kill doing what you want because they don't handle constant or heavy pruning well (and it sounds like you are going to cut a large central leader to make an open vase, which is why my old cherry tree split about 15 years after I had that idea), and the guava (which I just don't know about) fruit on last year's wood. Once you get your basic tree structure down your pruning will be replacing old branches when they get too big and heading back new branches to encourage fruiting and strength. You can bend the branches down to do the heading back and the branch replacement will be done at whatever level you decide your fruiting branches will come from. That level could be radiating from a central leader or it could be a system of scaffolds. I see a lot of overgrown "new wood" fruit trees and the reason is people didn't train them with the idea of branch replacement and to continue getting fruit they need to let the tree continue to get larger and larger. Let's say you decide your base will be cut at 4' and you will allow the trees to go no more than 10'. If the trees grow 12" a year or you head them back so they grow no more than 12" a year that means you will be replacing branches every 6 years. I don't know about zone 9 but 6 years is not a unmanageable branch. If it is you could decide to replace every 4 or 5 year branch and have an 8'-9' tree. If you are really stuck on having your trees only be 6' (which like I said above, there is no pruning reason to have to have them at head height to prune them since you will be removing well below the final height and can bend whips down to head them back) you would be cutting them off after every 2nd year. I'm not sure your trees would go for that, they may decide they don't have enough tree compared to root to bother trying to populate and growing tree is more important. I have a McIntosh that hates being espaliered to 5' and it's always trying to grow more tree instead of getting heavy with fruit. You may have to do some root pruning to make them satisfied with 6' of tree or do some other stress/extra dwarfing techniques to cause them to bear heavy so they don't have the energy to make more tree.

You need to spray in fall as soon as the leaves fall and preferably again in the spring at first bud swell. Any later does no good. Your spray this past year was too late. If you google peach leaf curl control you will get more info like below. Here is a link that might be useful: peach leaf curl disease and control

mama: It won't have any affect on the tree one way or another. Probably the fruit won't get very big even if you leave it till next year. I'd probably leave it just to see what that fruit does. You likely won't get cold enough to hurt the fruit this winter so maybe it will make a mature fruit next summer. Might be interesting to see and it won't hurt next years crop.

While citrus is young count the leave and divide it on 20. that is how many fruits you may leave on them to bear. On adult trees 10 leave is enough for photosintesing for one fruit. The better plant is doing with foliage - more fruits you will collect. So pay attention on a mineral fertilising of your trees and they will pay you back with the fruits!! That lemon of mine lost all leave in december and fruits never turn yellow - I had to collect them in april, so it could grow new leaves. This Meyer got 7 lemons This wild citrus is 5 years old, does not grow at all, but give me 2 fruits every year!! And it is very rare that you will collect more fruits than volume of your pot every year