Does this combo work? I've been playing it as if it did, but I'm not completely sure on this one. I guess the question is whether the card is considered to be "in hand" at all times.
Secondary question: if an opponent reveals Arden Lynn could they play her for free?
I don't see any reason why that wouldn't work, and likewise yes Arden could be put into play if discarded from Gamblo (not played mind you, best to keep these distinctions clear in the rules forum ). As far as I can tell from the rules/FAQ, the only thing that changes about a card when you reveal it is it's hidden/unhidden state. It's still in the same place (in this case, a player's hand).
From the FAQ:
To “reveal” a card, that card must go from a hidden
state to an unhidden state by a card or game effect
that uses the term “reveal.”