Regarding Flash, you're going to have to have that conversation with them, it's just a matter of when.
If CF and CF Builder are both on the same machine, you should be able to use 127.0.0.1 as your IP address. But again, I'm not sure what exact problem you're having with the debugger. It's not going to catch page errors like you described. That's not really what it's for. It's to catch logical "errors" that won't cause the page to fail but might give you unexpected results, rather than syntax errors that explicitly cause the page to fail.
Dave Watts, CTO, Fig Leaf Software