You can keep them out for 30 seconds without any harm. I've personally pushed to a minute to a 2 mins, but my internal alarm was going off the whole time. That said, they all fared fine (kept them in the livewell for a short while to be sure), but I wouldn't recommend it.
As for 'reviving' them - Do NOT rock them back and forth! You can damage the gills. Water is meant to flow in one direction over the gills, and that's not backwards. Instead, swim him around in a forwards direction gently (I like to do it in a figure 8), while holding his mouth without much pressure. He'll pull away when he's ready.