Excellent Checklist! Thank you!
IMHO I like to see the box and goodies that come with it (for older watches too).. This tells me that the watch is well taken care of, and may not been through too many hands.
Important parts to my list research a little before going to see a watch, there are small details that make one watch more desirable to another, ( like Meters or Feet first on a Sub. I learn't this the hard way after loosing a rare-er Sub Meters first Sub for cheap..)
Next is Matching numbers on Case, Bracelet, Clasp. And bracelet stretch.
And last is the Dial and hands original. Or are the original ones available from the seller..
Lastly. Does the seller have the receipt from where they purchased the watch from..
Hope this helps! Happy searching! Here is a site I love the read
http://tumblr.hodinkee.com/