Most customization points is the big win for me. I REALLY like to alter my browsers to fit my preferred layout and FF has done quite well at maintaining that capability for me. I get into Chrome and I find myself constantly going "Oh, there's no option for that... Oh, there's no option for that... Oh, there's no option for that... " to the point I close it in frustration yet again.
Absolutely. You would never be able to do something like http://conkeror.org in Chrome. At one point I tried to change some key bindings in Chrome, and I had to spend 2 hours recompiling the whole thing; it was an absolute nightmare.
Not quite. Mozilla is a platform with which you can build apps. Firefox is by far the most popular app running on the Mozilla platform, but there are many others, including SongBird, Thunderbird, etc. The bare executable for the Mozilla platform is Xulrunner, and that's what Conkeror uses.
Anyway, the one thing that keeps Firefox competitive is that they built a platform in a fast yet very awkward language, then they built an application on top of that using a much more pleasant, flexible language. None of the other browser vendors understand this; Chrome devs parrot the "but Javascript is too slow to build our UI in" even though they have the fastest JS engine in the world. It boggles the mind and cripples them in the long term for anything other than your standard point-n-grunt interfaces.
Exactly my experience so far, except there's _still_ no decent Firefox replacement for Chrome's Google Quick Scroll. I forget I even use that extension in Chrome until I end up constantly Ctrl + F'ing the hell out of search results pages in Firefox.
