Bob, the heat sink is up to the end user, and will vary by application.
John, the space between L1 and the pads is to permit the use of connectors like the small green 2.5mm screw terminals. For the final run I did in fact shorten the board a little, it is about 1-3/4" long.
I do like the idea of the additional diode pad under the D1 pattern; will likely add that to the design.
We need to remember that one of the objectives here was to stick with easy thru-hole design so that most folks (like me) can build it without too many issues.