Is this the first trip out since head gasket fix?
Did it start without a problem when you headed back in?
I don't think a small leak would cause your pressure to go down. That leak's going to be a PITA to fix: timing cover and all front accessories will need to come off. Could have been a blocked water passage causing temp issue. I'm sure you've checked/replaced impeller before the season started, so were there any vanes missing? As you know, the temp sensor is on top of the intake manifold and may not reflect the actual temp of the engine. So if it got to 180* up there, it could be a lot hotter in other spots on the engine.