Rule 5.2, para 2 suggests that you can be well out of command range, but as long as you have a continuous line of adjacent units (theoretically unlimited in number) running back from a unit into command range, you are still considered 'in range'.
Yes, but those units have to be from the same command.
That's what I assumed, and how I play it, and historically it makes sense. But curiously, the rules (5.2/5.3) don't specify that...
It is implied, since you only check command status inside an Activation (according to the sequence of play) and only one Battle is Activated at one time. It should state that explicitly, I'll make a note of that.