Disable HTML for non-admins, allow admins to post PHP code

I consider myself pretty good at Googling, but I haven’t managed to find a solution for these “problems” on WP3. If I missed the solution(s) in the support area and this is a duplicate problem, I apologize. Any help would be greatly appreciated!

I want to use WordPress as a CMS – I think it’s fairly intuitive, robust, and easy for non-coders to use. The only real problems I’m having, though, are these:

1.) I want to disable the HTML tab for non-admins altogether, and
2.) I want admins to be able to post completely unfiltered PHP coding directly (inline) in pages and posts using the familiar “<?php” tagging.

I suppose a third problem I’m having is that toggling between the Visual and HTML tabs strips any code that’s entered and so even if it’s put in once (using any number of plugins that supposedly disable the filtering), it gets lost eventually. I think this is a “feature” of TinyMCE, though.

I haven’t used WordPress since early 2 and at the time, I used the Exec-PHP to solve my second problem (I was the only user, so the first problem wasn’t an issue). Since then, I see a number of additional plugins that do something similar to what Exec-PHP does, but none of them do it as well. I assume that’s because WP is now more locked down by default and as such, it’s not as easy to disable the security features. If it would be helpful, I can post a list of all the plugins and plugin combinations I’ve tried that haven’t worked.

The reason I’m posting this in the general WP support forum is because I’m not necessarily looking for a plugin (though that would be preferred). I’m happy and willing to edit the core WP files to do exactly what I want and either not update WP or update and edit the core again. I would just like some guidance on what I need to change in order to do what I want and where I need to implement these changes.

Thanks in advance!

[ Please do not bump, that’s not permitted here. ]