Washers: The picture shows red washers under the stock hard drive. Are those rubber gaskets or metal washers (or something else)? I figured rubber would be nice for shock mounting and metal would be bad for shorting out things. The traces on the Travelstar 80's are pretty close to the screw holes, so I'm REALLY hesitant to use even the smallest metal washers I can find. And what height should they be?

I used hard plastic ones for mine they were intended to be used as shock spacers on an RC car. They were about one mm thick. I wouldn't use metal for fear of shorting.

Hot Melt Glue vs. Thread-Lock: What IS thread-lock compound and can I get it at Radio Shack or something? Or will a hot glue gun do the trick to secure the drive and cradle screws? And is it cool to use hot melt glue on the drive jumper?

The hot melt glue is to hold on the HDD cable and the thread lock is to hold the screws in it prevents the screws from vibrating lose. You can get thread lock at a auto parts store (usually called loctite)

For the screws I took mine apart and just got ones that matched the screws that were holding the existing HDD in.