Great discussion for August. *grin*
A lot depends on whether you haul the boat or not and what access you'll have to the boat and to utilities over the winter.
1. Which parts are done in the water/ On the hard?
I prefer to do everything in the water with the possible exception of the water system. Even that I tend to empty afloat if I am going to haul.
The last thing to winterize is the main engine which you do in the lift well. On most boats you can do this by dumping water into the strainer with the thru-hull closed so you don't have to pull the hose off the seacock.
2. One version talked about flushing the holding tank with bleach after pump out. That would require another pump out? Or is the anti-freeze just added to bleach?
Your pump-out people should be used to this. Many people (including me) want to flush the holding tank with fresh water as part of every pump-out. If you do that consistently during the year you shouldn't need to do anything else than a regular pump-out. If you want to do something extra I would pump out the holding tank, drop a whole bunch of ice cubes (at least a 5 lb bag, perhaps 10 lb) into the holding tank and go sailing. Tack a lot. Sail through wakes. The ice cubes will help, as much as anything can, break up any thing stuck to the sides and bottom of the tank. Back at the dock, fill up the holding tank with water and pump out again. The only anti-freeze you need will end up on the holding tank when you winterize the head. Remember you need to pull the raw water intake off the thru-hull and stick it into your antifreeze to do a proper winterization of the head.
3. Pictures at the Marina would indicate that most people leave the mast stepped. Is anything special done to the standing rigging? (Leave it tight?)
You can leave it be. When my boat is out of the water I ease the backstay adjuster but leave everything else alone.
4. All sails are removed (including roller furled jib?)
That would be best but isn't strictly necessary. Some yards won't allow furled jibs to be left aboard (due to windage issues and the potential for damage to neighboring boats if they fail). You can store sails on the boat or take them home. Leaving them on the boat is easier. Taking them home is generally easier on the sails (depending on storage at home) since it reduces the chances of mildew. It also makes access inside the boat easier for winter projects.
5. Are all the sheets removed and stored below or at home?
Same issues as with sails. Depending on the condition of your sails you may want to wash them. If you want to wash them you may do that in a tub at the yard or at home.
6. Do you remove all your cushions or just prop them up?
At least prop them up. For many people winter cleaning and protection is easier at home. Transportation is often an issue. If you are going to take them home I'd get them off the boat at the dock to save the effort of hauling them down a ladder.
7. Any major (or really important things I need to be aware of)? (I know batteries are removed)
Batteries depend on storage. If you are in the water or have utilities on the hard and plan to visit the boat regularly you can charge the batteries with each visit. This is helpful as it allows you to use boat systems during winter projects (charge phones, troubleshoot systems, listen to music, etc.). Most yards do not permit you to keep the boat plugged in unattended.
Run through your electrical panel and consider whether you have additional systems that require attention: refrigeration, deck wash, generator, washing machine, cockpit drains clear (not usually on the panel *grin*), etc.
Personally I don't use anti-freeze in my fresh water system. I bypass the water heater, drain it, pump all fresh water through the system, and use an air compressor to blow the lines clear. Oh - pull the strainers off water faucets; mineral build up on the screens is a major source of problems with recommissioning. I soak mine, including the shower head, in vinegar for a day and then tape them to the fixture they come from for recommissioning. Anti-freeze is a perfectly reasonable approach that is easier, but Janet tastes the flavor and smells it in the shower for a month in the Spring, thus the use of compressed air.
If you do haul the boat check for a garboard drain on your boat to drain the bilge and keep it dry. Don't launch the boat without putting it back. Check with your manufacturer or owners association to see if the drain plug should use Teflon tape or Loctite.
Any rigging inspection should be done before you haul. Most yards won't allow you up the stick while on the hard. I've been up masts on the hard for work before and I don't like it much. There are too many things that can go wrong so even if it is allowed try to avoid it.
Not strictly winterization but if you do haul it is a good time to run your anchor rode(s) all the way out and scrub the anchor locker. Check your chain for corrosion and your rope rode for chafe. Be sure all shackles are moused and if you have an all chain rode that there is an accessible sacrificial rope link between the end of the chain and the structural connection on the boat.
If you don't already have pictures of the bottom of your boat hauling is a good time to get them. Pay attention to thru-hulls and zincs.