Posted: 10/10/2013 at 16:51
Hello lusi, sorry to have left you in limbo. I wrote a long message earlier on, only to find that it was deleted because the forum had signed me out. Didn't have the strength to retype it straightaway. Here goes again.
I think the best way for you to find the answers to your questions is for you to Google "RHS apple pruning". The RHS website deals with both summer and winter pruning plus why it is done, how to do it and when to do it. There is also a section on renovating old trees. There is so much information needed to answer your questions that I think you will need to read it all at your leisure and take a bit at a time.
I have never done summer pruning because all my trees are full size ones. As you will see from the website, summer pruning is generally done on what is called restricted forms, in other words shapes that the tree would not normally wish to grow into, such as cordons and so on.
I would think that there is little danger of your trees lacking a pollination partner. If you live in a town or suburb you probably have neighbours with apple trees. When bees are about they can fly for two miles to collect pollen and nectar.