I've been messing with autohotkey recently, pretty sure you could use that to make an autosave (save every x mins). dunno about saving progressive versions though
Maybe you could avoid the "can't go back enough into history to save the right version" with working with history snapshots, never really used it myself, but i think this could save you if you do think to do some at important steps.
the only situation really it would avoid in photoshop is that old 'do you want to save?' chestnut. yes. I mean NO! NOO, I meant save as! and you go back in your history steps and no, you've done too much editing to get the original back
Not that I know of. It's a good habit to just save every so often though. I have actions set up while working on a texture, to save out revisions of the PSD and TGA with the push of 1 action button. So I do that like every 10 minutes. Just need to break the habit of not doing it, I suppose.
It should be possible to write a small script or app that saves the currently opened document periodically, using Photoshop's COM interface. Like Xoliul, I also have very little experience with Photoshop crashing.
Photoshop is pretty stable but the computer it's running on might not be. Honestly it's just pathetic that any major art/production program these days doesn't have auto-backup. It's 2009, people! We figured this shit out a decade ago! It's not even a difficult feature to implement. Timer, increment number on file name, use…