Digital Light & Color

Normally arrows are used to point the labels to the right spot. I need to label the arrows instead. Is there a way to for instance place a label near the middle of an arrow?

Not automatically -- you can always create a separate text box without a line and drag it where you want it.

I imagine that pairing/grouping two or more objects (so that the label moves with its arrow for example) would be complicated...?

Yes.

It is also complicated to position text so it doesn't cover other text boxes or cover its own or some other arrow. And one might want rotated text that aligns with the path of the line or curve.