http://www.penguinmagic.com/specialorde ... hp?ID=5593
These are most likely the cards you are considering. I have a deck of them myself.
They are poker size, plastic coated, and the backs and faces are (obviously) one-way. The coating is actually not really that bad, and they will work with most sleights, as well as spread fairly well (better than any plastic-coated cards I have used, anyway). As far as the coating goes, they are about like Aviators, if you have used those.
The one-way backs could screw some things up, but if you are doing something in which that can be kept in control, or if it just doesn't matter, it'll be fine.
Aside from that, they come with instructions for tarot readings, which may be useful for what you are going to do, whatever that may be.
Each one has a small description on the front, as well as the playing card and tarot card represented.
So there you go. As for gimmick, you'd have to gaff these ones yourself. I don't know of any pre-gimmicked tarot decks.