Can starting position extend over the line?

It does not say if a robot has to be behind the white line, just that part of it has to touch the bar. Would having a wheel over the white line be OK? (e.g. aligned to the field wall aimed at the mobile cone down field on the colored tile).

Maybe there’s enough room to touch and not be over the white line.

Yes this seems perfectly legal

The tape line is 18.5" from the bar. I would imagine that as long as you are touching the bar, any orientation of the robot is allowed as long as you are touching the bar. Since a robot that is exactly 18" by 18" is approximately 25" diagonally, it is entirely possible for part of the robot to be over the tape line if oriented at an angle other than 90° to the bar.