Viddler

Thats why the first plugin I install in FF is scrollbar-anywhere. With hat you can scroll up&down + right&left by just pressing the right mouse button. It scrolls as long as you press it (quasimodi).

mobile interface limitations

Where is the adress-bar again in this conceptDoesnt the iPhone show the adressbar and below the searchbar alwaysSeems like an very important task for me -- like bookmarking ore more important. So I dont like the idea to have it hidden in a submenu...

I like the search engine query continuation idea.

TOP is better; doesn't make you focus on the bottom of the screen that you don't normally look at. Plus its where the other search boxes exist in both web browsers -- address bar and search engine box -- and in search engines.