Wow.. you're going at it hard here....
First: I keep register globals off on all of my servers for security reasons. Dataface will work fine with this setting.
I'd be a little wary before changing too many of the variables in the template. The $ENV shoud be $ENV and not $_ENV, for example.
It is painful thinking of the pain you must be going through trying to get this working, but my best advice, before taking the hatchet to your site any further, might be to try installing the default version of LCMS on the new server and see if it has the same problems. If it does, then we can try hatcheting that (rather than taking your whole site apart). Certainly the problem is just one simple setting on the server's end, or in the configuration.
One thing to try also, is try entering the explicit address to the page. e.g.
http://www.archomai.co.uk/index.php instead of
http://www.archomai.co.uk .... it could be a problem with not picking up the page name properly and getting null page....
-Steve