Using the Decisions it would be possible to perform a routine along the lines of the one DB did with Stephen Marchant. However, I'm as sure as I can be that this was not the method that Derren used (and I say this as an owner of Decisions and I've viewed the Marchant video recently on YouTube). I like Looch's routine and I liked Derren's too.
Can the cards be picked up by the spectator?
The simple, cover-your-backside-can't-be-contradicted answer is no. In reality, in the context of a routine, if you know what you're doing and can employ certain techniques then you can leave the spectator happy that they could pick up and examine the cards.