Are Compressor droplets "moveable" from computer to computer?
If you transfer from one computer to another or download them from the we , do they establish the correspnding custom setting within Compressor, or do you have to create the compressor setting manually?

I'm not sure anymore, but I think I did just that: made a compressor droplet on 1 of 2 Mac Pro's who both had to render different video's to the same format, and then used it on the other computer. If I'm not mistaken, this just worked, except if you make a droplet of something (Flash for instance) that has a compressor-plugin that the other computer doesn't have.
But if they both have the same version of Compressor, I'm guessing this shouldn't be a problem. (and it's one of their advanages and I'm guessing one of the reasons the feature is there in the first place)

Are Compressor droplets "moveable" from computer to computer?
If you transfer from one computer to another or download them from the we , do they establish the correspnding custom setting within Compressor, or do you have to create the compressor setting manually?

You need to have the same version of compressor on each mac, but if you can hack into the droplet and remove the settings file and have that then appear on another mac.
Just 'Ctrl' click on the created droplet and 'show package content' open up 'Contents' / 'Resources' / 'Settings'. The settings file is in here.

I archive a droplet with each job, just in case I have changed the base settings as I have a long list of custom settings in compressor so its handy to know I can always get to the settings file.