Or 'authority:' exousia not dunamis. More than authority, but not simply dunamis; it is more than dunamis, as it includes the right to exercise this. Hence 'power' is nearer to it in English: dunamis is the ability to do a thing. Cf. Luke 4.36.
Very probably the Hebrew word for the Greek term Zelotes, 'Zealot:' see Luke 6.15.
Absence of the article in the original gives the force of 'any.'
Lit. 'the:' it hardly alludes to the house in ver. 11, for ver. 13 seems to preclude this. It is going into the house, in contrast with the street.
Here, and in the parallel passage, Luke 12.4, we have apo, 'from.' It is not so used elsewhere that I know of in the New Testament. Here it may have the force of 'shrinking from through fear.'