Tried the third patch and it does stop the tips of "f's" being cut off on both my side loaded and kobo loaded kepubs.
I also tried it with the top padding set to 2 and bottom padding set to 0 in the hope it would correct my pet complaint of marks at the bottom of the page with corresponding bit missing from the top of the text on the next page.
On most pages there was no improvement, but on pages which started with a new paragraph then that page did not have bit's missing from the top of the text. Also the previous page did not show corresponding marks along the bottom. I suspect this method can fix my pet issue of marks on the bottom of the page if only the patch can be made to add padding to a page in place of just to a paragraph.
Any chance GeoffR ? You've done a great job so far.