Xauth and Xseession question

[Caveman <biocorporation-1@optusnet.com.au>]

Hi,

I have googled around but there seems to be very little on this.
I was reading about xauth and related stuff here 
http://www.xs4all.nl/~zweije/xauth.html

Now I have a couple of questions which I cant seem to find a answer too. 
The first one is that I have a php script which I need to be able to access a 
X session. Now I can run xhost + to allow everyone. But is there a way to 
allow every hostmask for a certain user?
For example. The php script runs on a webserver. The webserver username is 
webserve. I want to allow the user webserve access to all Xsessions from any 
address. But for security I don't want other users to be able to do the same.

Second is it possible to connect to a ALREADY running Xsession ? For example, 
I have box A and box B. I start kde on box A. Then I login to box A from box 
B can I access that Xsession ? 

And thirdly I am wondering how to make perminatant setting changes for 
something like Xauth. How would I allow all hosts access to any Xsession?

Thanks guys. I hope I make some sense.

Caveman