I never get 600 good miles out of a pair of shoes (though I've met others who squeeze that much out of them). Mine usually last 300-400 max, sometimes less if I'm running on asphalt a lot. Getting new ones may help.

I am prone to compression blisters on toes 2 and 4. To prevent it I just wrap the toes in regular ol' medical tape before every run. Just a little tape. When I do that, I don't get blisters. Have you tried wrapping the ball of your foot with one layer of tape? Of course you may want to wait until the ickiness goes away.

Oh, and my big toenails are permanently black & blue from skiing and riding and now running again. My answer to that is a nice pedicure with bomber topcoat.