its been a while since i've worked on these so i could be wrong...
I think the tube that goes out the bottom into the valve cover is the pcv valve. They had issues with throttle body and pcv valves freezing in cold weather. The moisture was creating cream colour sludge build up. Thank daiwou for engineering that.

that valve in your hand allows coolant to warm the throttle body and vacuum/air line that pcv air flows through. The name of it I can't recall. GM parts dept will know.