What kind of dedicated server/bandwidth will we need?

[cd34]

I would start it, run with it, watch the load and bandwidth, increase your plan as necessary. I wouldn't get too over-the-top with ordering a bank of servers until you have the concept working. The Rsync/Round-Robin DNS can come much later.

You can embed the affiliate's url in there with a mod_rewrite, something like:

Surfer sees: http://site.com/fhg/affid.html

You code for: http://site.com/fhg/index.shtml?affid

Your .htaccess (or preferably put in the config) would be:

RewriteEngine on
RewriteRule (.*)\.html$ index.shtml?$1