For LaTeX templates...
There's a "reader.sty" for setting the page size for the Sony in this thread here:
https://www.mobileread.com/forums/showthread.php?t=12872
based on this one for the Illiad:
https://www.mobileread.com/forums/showthread.php?t=7529
neither of those have anything to do with fonts though. The default Computer Modern is not very reader-friendly, I have to confess. I've used the kpfonts package for making ebooks with LaTeX, and it looks nice. Utopia from the mathdesign package might work out well; I've been thinking of trying it.