NightWind's Card Searcher

That is the (Active) ability he's talking about, and it's nowhere in the cards.csc file, Horo. And that's just a search on cards containing the text "(Active)", NOLDER.

As for your question 2, searching on ability text is the only way unfortunately. This search does cover everything though and would also cover all currently planned upcoming cards too.

I think this is how searches for Fleeting, Touch of Death, Second Life and Bounce work, although these searches do actually miss cards where the ability is hidden (First Avrillian has hidden Fleeting for example). I don't think we'd ever hide Active though, as it'd just be too frustrating not knowing why you couldn't cast a spell half the time.

Incidentally, the search for bounce misses a lot of cards from it, due to it being worded in a number of different ways at the moment.