Re: Dock vs. mooring
The amount that you need to fully pump depends on how long the lines are. On my 28' boat where there is a 3' of 1.5" line between the toilet and holding tank it doesn't take a gallon to flush, the volume of the line is just under a quart. Our 20 gallon tank is good for 6 or 7 days for the two of us.
This thread and the thread on dealing with dock lines has taught me how regionalized boat storage can be. Mooring balls aren't that common for permanent moorage around here (Seattle), I primarily see them in front of waterfront houses for smaller boats. I've never seen a dock without cleats and where you are tying off using pilings either. Obviously both of those things are much more common in other areas. Another big difference is that boats are stored in the water year round here, but are usually hauled out in the winter on the east coast, even in the Chesapeake where it rarely freezes.
boats that I sail on regularly: Pearson 28-2, Rondar 505, Yankee 30, Blanchard Junior