I have the same bike as well. I have reached 25-26 pedaling very hard down a hill. A far as range goes, I did a ride that was 30 mile on hilly terrain. I used the lowest level of assist and still had two bars showing on the battery.
My take is buy the bike you like to ride the best, and can still afford, a year from now you will not care how much you spent. all this analyzing time could be spend riding your new bike!
I got the handle bar at Performance Bike. If you have one near you, they could install it as well. It really took less than 1/2 hour to do if you have a set of metric Allen wrenches.
The bolt is for locking the battery to the bike(with a small lock). Mine was loose when I first got the bike but it has stayed put since I tightened it up.
the shifters are one for up shifts and one for down shifts.
I changed out my handlebars to a wider set and added ergo grips. That made a huge improvement.
see this thread:
http://electricbikereview.com/community/threads/new-nitro-owner.1963/
It states it on page 25 of my manual:
How to ride
Before you turn the bike on and start riding, you should
understand the way the pedal torque sensor works. Mounted
in the drive-side rear dropout, the torque sensor measures the
very slight deflection in the dropout plate that occurs when...