Shedding can last anywhere from 3-7 days...A couple of days after the eyes turn blue/hazy they will return to normal...A few days after this they will shed..
Handling corns during a shed is pretty much up to the corn's attitude that week...If the corn will allow you to handle it, then by all means handle it..If not, then you will know when you try to handle it...
You can even feed a snake during a shed...I feed my corns whether(sp) they are going to shed or not...Some corns may not eat while shedding but most will...I feel that by feeding a snake during a shed it may actually loosen the old skin since the meal is stretching the snakes skin out then back in...This in my opinon makes it easier for them to shed and in turn they usally shed in one peice..Although this also has to do with the proper humidity/care of the snake...
If the air in your house is kinda dry or you notice your snake is having a little bit of trouble shedding it never hurts to give them a bath in lukewarm/room temp water...You can even make a moist hide by using a butter container with a hole cut in it, that has damp paper towels/or moss in it...
HTH,