if I download the Adobe DRM ePUB version, does the book get stored on my PC (can I select where to put these back-ups)?
When you download an epub file from Kobo it's actually a small file with a .ascm extension. You save this file in a directory of your choice.
Double clicking this .acsm file opens Adobe Digital Editions application (you'll require this application already loaded on your computer) and creates the DRM protected filename.epub file which is located automatically in:
C:\Users\username\My Documents\My Digital Editions\filename.epub
This book file can be dropped into the e-reader with ADE, Calibre, or Explorer.