Wow, looking at you upside down photos gave me vertigo and I fell off my chair
I would suggest that you give the right side of the engine a really good high pressure cleaning and then
check for that coolant leak with an inspection mirror or a borescope camera (they can get into all those tight places).
As far as leaks on the left side of the engine there are coolant hoses running all over the place. Pulling the intake manifold is very straight forward and not terribly difficult. The only problem I ran into were the fuel injector connectors that had become very brittle and some broke apart. I replaced them all with new style “push to release” connectors with pigtails, so a bit of soldering was required.
With the intake manifold removed any coolant leak should be fairly obvious. Of course you don’t want to remove and reinstall your intake manifold before you determine if the head has to come off then you’d have to remove the intake manifold all over again.
Number 3 spark plug is the only one that looks a little suspect with the side electrode not being that tan color like the others.