It is better to use lower-case style names in the CSS as it's very easy to mistype and get the case incorrect in which case, you cannot be sure that the reading software will not need to be case specific.
As for page breaks, the only place I ever use them is for endnotes so I can have one file and be able to show only one endnote at a time. Otherwise, I prefer splitting the XML flow where you would otherwise have a page break.
I've seen some ePub with chapters merged together and then when the flow is too larger, the text continues into a new flow. Very messy. Besides, with iBooks being a PITA regarding page breaks, it's just easier to start a new XML where the page break would have gone.
Last edited by JSWolf; 01-15-2013 at 06:10 PM.