Thought it was a six hour job. Regardless, still a chunk of change.
As for the coolant, you should have 50% water, 50% coolant. It doesn't matter what's in the overflow tank - it matters what's in the radiator.
Change the oil, get a nice filter, change every 3-5,000 miles and put in copper spark plugs (for cheapness) and change them every 10-15,000 miles since burning coolant will eventually ruin spark plugs. Keep an eye on things. Unless the gasket is catastrophically borked, the vehicle will operate. When it's catastrophically borked, the engine may hydrolock. So... when things get bad and oil gets milkshake-y, that's the razor's edge you'll be driving on. Try not to let it get that bad. I'm by no means an expert, but unless you're seeing major issues yet, I'd say you might have 30,000 miles on the clock before d-day. Just... do the gasket job before then.
