Thoughts from the pile
I generally cut 40 to 50 cord a year off piles of tree length. I'll offer my advice, you're most welcome to follow all, some or completely disregard as the rambling of some old guy that's full of crap like most.
First PPE. You should have and use the following. Ear, eye, and leg protection. I wear earmuffs, safety glasses, and Labonville full wrap chaps. Using a helmet is up to you, I find them cumbersome and uncomfortable for use on a pile but they are certainly a very good option. One of those YMMV situations. I've also found when the sun hits the mesh face shield at certain angles the glare will blind you, again up to you. As previously mentioned, a cell phone, on your person and accessible is a must. Always send a text to someone letting them know where you are and what you're doing before you start if working alone.
Boots should be heavy leather 8 to 9 inches high. The extra height over a hiker will keep your ankle from rolling under. You'll find when cutting or working around a pile of cut rounds they'll encounter situations where they want to bend in ways they're not supposed to.
You'll need 2 saws, or at the minimum an extra bar and chain for the one saw to get yourself out of a pinch. (This is a situation where having an outboard clutch becomes a major PITA), Stay with a short bar, 16 to 20 inch should be fine. I actually run a 17 and 13 quite a bit. Wedges 5-1/2 to 8 inches are handy too as long as you remember to bring something to drive them with.
As to being off the ground, if the driver / boom operator has any clue as to what he's doing he should have placed 3 runners minimum perpendicular to the direction of the pile to keep the wood up off the ground when he stacked it with the grapple. If he didn't look for a new guy next year, or be sure to be there when you take delivery so you be certain it's done properly. The runners don't just keep the wood from ground contact, they provide clearance as you cut through the bottom sticks. This method only puts 3 lengths in contact with the ground as opposed to the entire 12 to 15 that make up the bottom tier.
Now let's start cutting. Depending on the stack you may go down the length or cut on the end of the pile and work your way towards the center. You'll figure out what is working best as you go along. Watch the kerf as your cutting. If it starts to close get out immediately and come in from underneath. this is where knowing how to bore cut comes in real handy. As you're cutting be sure to watch for any signs of the pile shifting above. Sometimes it's just a real subtle rocking. See any signs get out fast and assess the situation prior to continuing.
Don't get ahead of yourself. Cut a tank, no more than 2, and then either move the rounds out of the way or I split them. When taking rounds off the pile if they don't come freely,don't force them. That one round may be acting as a keystone keeping the pile from rolling. Keeping the area around the pile cleaned up will greatly reduce your chances of slipping, tripping etc.
Always be balanced when cutting on the pile. I can not emphasis this enough. If things start to roll you need to be able to move, and you can't do this when you're practicing your log rolling skills. Don't reach with the saw. It's tempting but if you're reaching you're not balanced. The pile will get cut much quicker if you take that bit of time to be safe rather than spend 3 months on crutches.
Never try to take the pile down with a peavey or hookaroon. If it rolls, which in essence is what you're trying to do, you're way to close. Log piles do not roll in a straight line nor does just the one log roll, they like to bring unexpected company when they come down. Even if your off to the side you're in harm's way. Go to Harbor Freight and get a 20 ft. minimum tow strap. Wrap one end around the log where convenient and use a truck, tractor, SUV to pull from a safe distance. If that log won't come, pick another and try again. No vehicle access, a come along or 2000 lb winch anchored to a tree with a battery works wonders. You just need to break the log free, gravity will take over and be you're helper. If you need to roll the log to cut once it's free of the pile then the peavey or cant hook is fine.
That's my 2 cents, hopefully some of this is useful. Best advice is to go slow, and think first before doing anything.
Here's my summer project for sale during the 2015/2016 heating season.
Take Care