Trip (MA81), can it be used on Step-and-Attack? Hit loc for fall?

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Greetings

The technique Trip (MA81) rules that it counts as a parry, and can be used on a Slamming foe. It can also be used to intercept a foe running (not merely a step) past you, through your hex or an adjacent one.

So would it be reasonable to use under other circumstances?
-If a foe steps in and attacks you? As an interception it can't be used on merely a step, for needs to "run" which I interpret as Move 2+. So if a foe does a Step-and-Attack, that sounds like a no. Unless, maybe, it is a Committed Attack with double-step?
-If a foe charges you? Meaning an AoA, which allows ½Move (forward). So if the foe actually moves 2+ yards, then it sounds ok?

And how about the Trip itself, how does the foe land? Falling down usually means prone/supine. There is no mention of any damage form the trip, as opposed to a Judo Throw. But I'd like to have had the option of making the tripping foe hitting his head on something. Like if you fight in a hallway, you could direct the trip so his own momentum carries him head first into a wall.
Again, I'm guessing no. What I want actually sounds not like a Trip, but rather just a Judo Parry followed by a Judo Throw as my next move.
And by TG terms that would be a defensive throw.