No one has asked but is this Kobo Touch properly up-to-date with firmware? Using
www.kobobooks.com/desktops? The desktop should report 2.0.3 and the Device Information report 1.9.9; the data and time on the device should reflect current time (important with library books); the advice on ensuring the Kobo Touch is registered to the same account (ie email) as Adobe ADE and Kobobooks.com has been mentioned.
Corrupt books through non-commercial sources are possible and can gum up the works. They are easier to trouble-shoot going slow. Users should never have to tinker with .sqlite files so if you (or anyone) is already that far down the path, it's time to regroup and try to start at square one -- recheck all the basics and then add a book at a time.