That's about it, except for maybe Web Proxy chaining scenarios. Making an ISA 2004 into a single NIC box is like taking a Porsche and removing three tires. Sort of criminal to cripple such a power machine, in both instances.
No problem. Web caching is a powerful feature and I'll probably writing more extensively about it than I did with ISA 2000. There are a lot of misconceptions regarding how ISA Web caching works viz. WCCP, ICP, etc. and I'll want to clear those up early on.
There are a number of scenarios that aren't generally covered, such as how to integrate the Web Proxy with existing WCCP or PBR Web caching environments. I have a big list of caching articles that I'll be writing over the next serveral months that I think will really help people integrate the ISA Web Proxy in an existing environment.