I've had calling issues with other phones (not the 8800 though) and they were primarily related to the towers. From my office on T-Mo I used to have full bars coverage and drop the call.

What I'd try doing is making a lot of calls from a location farther away from your house. See if you get the same echo and dropped calls. My guess is that it's probably your tower.

As for the backlight, that seems to fluctuate somewhat for me as to whether it's perfectly set. You can always go to full bright by tapping the power button once.