Photos come home with me and immediately get transferred onto both the laptop and the desktop. One of them is then the designated workplace for dealing with those photos, and when I'm done with the album, everything gets consolidated on the desktop. On long trips, I take the laptop and transfer onto it every night, and also back up to a 64GB usb stick.
The desktop photo library gets backed up continuously off-site to Crashplan. I also have two hard drives that do a encrypted backup of all my stuff (not just photos) and one always lives in my desk drawer at work, alternating every month.
It's better to reformat a flash card than to do "delete all." Reformatting is one quick step that just writes a new, blank filesystem (do NOT do "low-level" if that's an option on your camera). Doing delete-all performs a whole lotta writes to the card, rewriting the filesystem info repeatedly as each image is deleted. It also uses more battery. The only caveat is with certain devices …*for example, my Contour helmet-cam has to register a bluetooth address with the desktop software and keeps that address in a file. If I reformat that card, the file is lost and I have to reconnect the camera to the desktop software to reregister it. Very annoying to find out the hard way.
As for the phone, I have an iPhone and use Photostream. Any photos I take, once I hit wifi they're uploaded to the servers and the most recent 1,000 are stored. On my desktop, Aperture (and iPhoto will do this to) can be programmed to see the Photostream, but can also be separately set to automatically download it, too. So any photos I take on the iPhone (or iPad) will eventually make their way into my photo library with the only intervention from me being when I fire up Aperture for my regular uses.