In Cubase 5 you can hold down CTRL and use the scroll wheel to zoom.
It would annoy me if it did it all the time.
To go back to the beginning I just use the . or period key.
What really helped me was I spent the $20 or so and go the hot key stickers for my keyboard. The dedicated keyboards were just too expensive for me and I wanted a wireless one as well.
Both Reaper and Cubase are very customizable. I still think Cubase has an edge over Reaper with the Scoring, Control Room, and other things.
Now if I could just figure out how to get Cubase to do Tab to Transient like Pro Tools.