Technically its for 2 hosts, but right now I was doing them in seperate irules since the original sites are seperate VIPs. I dont imagine I would need to go beyond a single host rewrite per site. (Its just used for developers to test a beta version of that site using a production caching layer)
The number of uris would be huge, although they all would use the same placeholder guid, just the content at the end would change, I wouldnt want to map them all specifically since its over 100,000 different items and fairly dynamic.
I dont think I will need to rewrite content inside the doc, in general the link should only be calling to specific content, like css / js files.