What is wrong with numbers
(as long as you did them so they ASCII (alpha)sort in case your OPF gets damaged.) They work just fine with the reader device.
I find named files
can be handy for copy-edits, but if you have used the a scheme that allows auto generated TOC, even that is not needed. Just click the TOC (NCX) item to get to the file where the edit is needed
I never understood why some publishers encode all the component the file names with all the metadata (ISBN_title_Author_sectiontype-sequence).
(do the BPH hand out pieces to different copy editors?)
EPUB is a package, you usually work
inside the box 
Except for developing a cover or publishers boilerplate stuff that may come from external sources and need to be married up with the proper package, this seemed unnecessarily long winded