Ok, it seems you're not quite 'getting' it, so here's another approach to the description:

when a user browses to your top level url, here is the sequence of events:

Browser sends...

You're sounding like a broken record.

A single response can only have a single MIME type.

Therefore, you need 2 distinct responses.

The first response would be the text response, which includes an...

There's no reason why a DB hosted image source can not be fast and efficient.

The problem re ASP mime type is a nonsense also, since if you are returning an...