I simply wouldn't use track arms because the servo motor needs enough torque to move the robot. Large strong servo motors are very expensive. I'd just use a shaped track personally.
The exception is for little robots that you can carry in our arms, then you can use the most expensive RC servos available.
Yes it can except for stairs that only have horizontal boards and no vertical boards (almost nothign but legs can climb those steps or robots with enormous tall and long tracks or wheels).
Even robots with a regular straight track can climb stairs. Shape tracks have an eeven easier time getting on the stairs. Once you're on the stairs the two are about the same. The main thing is that the robot has to be long enough to span several steps.
"Friction is independent of area in case you didnt know." so in some design links which u gave, usage of wider belt and narrow belt makes no difference? Surface area in contact makes no difference in grip??
If i use a belt of 2cm wide or 4cm wide in my design it makes no difference?