10/1/2007: The turn you cast Colfenor's Plans, you have cast (at least) one spell that turn. After it enters the battlefield and its last ability goes into effect, you can't cast any more spells that turn.
10/1/2007: If Colfenor's Plans leaves the battlefield, you can no longer look at or play the cards exiled by it. That means you can't distinguish them for any reason.
10/1/2007: Playing a card exiled with Colfenor's Plans follows all the normal rules for playing that card. You must pay its costs, and you must follow all timing restrictions, for example.
10/1/2007: If an exiled card has morph, you may cast it face down.