Thanks, Dan, for all the hints given, the do's and the don't's, the Facebook PHP compiler. I'll look into these things.
Remarks made about PHP may seem to indicate that choosing PHP for this project is not such a good idea. However, in defence of PHP, there are resources on the internet that show a programming language's popularity, and the good part is that PHP ranks third after Java and C. See http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html. It shows that PHP is very popular. Of course, popularity does not say much about quality. Yet popularity has helped me a lot while writing code in PHP since it is very easy to find code snippets on the internet that do what I was looking for, and this saves a lot of programming time.
I do share your concerns about the need to keep the existing Gtk code for current Bibledit available. My intention right now is not to stop maintaining it till at least such time that bibledit-web equals the power available in bibledit as we know it.
Thanks you all, guys, for thinking about this new thing.