Evinrude list the 90's prop nut torque as 120-144 in. lbs (or, for you folks to our east, 13.6 to 16.3 N-m.) You'll need to block the prop from spinning with a piece of 2x4 lumber, then crank on the prop nut. If there is play in the prop (fore-aft play, that is) after tightening, you'll get cavitation and eat metal bits from the prop (don't ask how I know...)
Bilge pump: Go bigger than you think you need. I've got a 1000GPH pump, and wish it was bigger. You will not be able to use it to flush the motor (not enough pressure, most likely not enough water, either.)
Flushing adaptor: Don't know. The 2006 manual looks like the hose screws directly into the back of the motor. The manual states that you do not need to run the motor on the hose; it also says that you may run the motor on the hose, but that you may get a CHK ENG warning light. It says the motor will shut off if you have insufficient water to it. I would advise not running, but that's just me.
No need to anti-foul the hull unless you're mooring it long-term in the water. Trailer boats aren't in long enough to foster growth.
Don't know on the rest of the stuff.