I love my Glo, I've had one since they launched and it's the best e-reader I've owned.
I second the use of Calibre, using it to sideload books will add the full cover images in your library and lock screen, as well as most of the metadata. I also have mine set up to create collections (shelves basically on the Glo) based on the tags, but I keep pretty tight control on them and use my own tags for sorting.
I'd wait on any of the hacks and patches around this forum until you're familiar with it, honestly I went years with just the stock firmware and it worked great, the hacks don't add any features I'd consider must-have.
Wireless syncing will eat like 5% of the battery, but with wifi turned off the battery will last months on a charge even with heavy reading.
Also Kobo has a bunch of contests and there's a
thread with coupon codes that's usually kept up to date, though they don't work on all books (I think any that are agency pricing are excluded from coupons).