If you set up the Kobo Glo with the same Kobo account as you use with your current Kobo, then, all of your Kobo books will automatically be transferred to the Glo during the setup process or when you do the first sync.
If you want a version of your Kobo books that is compatible with Digital Editions, then, do this:
1) use a web browser on a PC to go to
www.kobobooks.com
2) sign in using your Kobo ID (e-mail address) and password
3) go to My Library>PURCHASED
4) click on the blue button that says ADOBE DRM EPUB beside the book or books you want to download.
After you have done this, for each book selected, an ACSM file will be downloaded to your computer. Open the ACSM file and it will start a process that will download an EPUB file and will open Digital Editions.
Notes:
1) you can also access your Purchase History by clicking the account icon in the Kobo Desktop (top right, middle button)
2) if you transfer the Digital Editions version of a Kobo book to your Kobo reader you will end up with two copies.