PHP is HTML with a .php extension and if you add it PHP tags.
You can actually have a complete HTML file with a .php extension that has NO PHP in it at...
So all you would need to do is have Frontpage, use .php as the extension of the files (don't know if it can do that though as I've never really used FrontPage).
What do I use....
Universally accessible tools that I can use from anywhere I have access to the Internet including my cell phone...(don't do that often).
Notepad like editor (I use ConText normally)
FTP client
Of if I don't have that but can ssh into the box
vi (vim or other similar text editor)
I've used large content web management systems many times in the past Adobe GoLive, Dreamweaver etc.. but they all have one big fault.... if you are where they aren't you have a problem updating the site.