Irregardless of what you are doing in your InDesign document, an ePub export has to follow the very strict rules of HTML -- and not even the full set as we know it from (semi)formatted web pages, but a subset thereof. There is absolutely no guarantee you can export all you can do in InDesign to an ePub, in fact, there is only very little that survives this radical downsaving.
Besides, I'd have to check but I don't think Adobe intended InDesign to be the once-and-future ePub Layout Engine. Rather, its export is to facilitate cross-publishing, and helping you on your way creating the eBook of your (e)Dreams -- but you have to do the finalizing with some better targeted software.
But, basically, your premise -- that you can put something "at the bottom of an e-page" -- is wrong to begin with! A proper eBook can be reflowed, the font and its size can be changed, the reading window can be resized (on some devices) or rotated from landscape to portrait and back (on some devices). So there is no concept of a "page", and everything you pull off to "be" at the bottom might appear at the top for other views.
[Jongware] is correct. The most important feature of an EPUB is its reflowability. You might be viewing that page on an iPad screen or an iPhone screen. The viewer could have set the font size to be very large or very small. There is no way to guarantee how many "pages" the display of a certain number of lines or paragraphs will take.