Creating an EPUB file is a lot different than creating a print or PDF file. It's highly recommended that you do some study on how to prepare files for EPUB. Two good sources are:
(1) EPUBs by Elizabeth Castro:
(2) Videos by Anne-Marie Concepcion on Lynda.com for InDesign CS5 and CS6
Short answers to your questions:
(1) To creating the spacing you want you need to religiously paragraph styling that sets space before and space after. You CANNOT rely on white space or special characters (e.g., break characters) which work in a print document.
(2) To break a page (which means create a new XHTML file) can be done in these ways: (a) specifying which paragraph style(s) will force a break. This is done in Paragraph Styles menu > Edit All Export Tags > Split EPUB, and also setting Split Document in EPUB Export Options > Advanced. (b) Putting files into a book file. (Each chapter will start a new XHTML file.) (c) Setting Break Before or Break After in Object > Object Export Options when you have an image or rasterized object.
Thanks Steve, EPUB or print, it seems rather incomplete for a design program not to recognize a page break. I'm trying to think of how to space before and after every different length of poem and space between each line and stanza. That hardly seems feasible when the spacing is recognized during placement and import. I did try several options in the export dialogues.