Thank you for your inspiration.

1) If you crack the plug off, can that top valve cover be removed with the engine still in the car?
I can barely see down there, and no side view, so it's not obvious to me.

2) It took me longer than I care to admit just to get the boot seated again.
So, threading something seems a whole different ballgame.
Just keep trying until it catches?

3) Can you fish it out through the hole? Fingers? Magnet tool?
When I stuck my finger in there, I could barely touch the spark plug tip.
So, I can easily envision it falling out of reach. Then what? Step #1 ?

I loosened the 3rd spark plug today.
All 3 on the left side came loose very easily, so I am no longer worried about seized plugs.
A size 10 hex key socket bit was easier to maneuver than the allen Key.

After #3, I realized I had not re-installed the first 2 boots correctly.
I pulled them, and this time, I got the metallic "snap" sound when fully seated.

and..............
I was about to try fully removing a spark plug and reinstalling it, but chickened out at the last second.
Just worried I would not be able to re-thread the spark plug back in.

So, I did take a closer look at the spark plug valve cover (Is there a name for it?)
If I could not re-thread the spark plug, I could just remove the 6 bolts, remove the cover,
and getting a much easier access at rethreading the spark plugs, right?
In fact, is this the preferred method? 6 bolts might be quicker than blind threading.

I always remove the valve covers to access the plugs. Easy as pie.

Ok, that's good to know I can just remove them, if I get stuck.
Do you need to install a new gasket each time you remove the upper valve covers to access the spark plugs?

What exactly are the upper valve covers for?
Are they sealing oil like the lower valve cover?
I'd think not since the "dust boots" on the spark plug boots are not really sealed.

If you're careful, you should be able to re-use those upper valve cover gaskets if you need to remove the cover for any reason. I can see you doing a valve adjustment next, so you might as well order the gasket kit and have it at hand if you tear the gasket somehow. Yessir.... you're in for lots of fun doing your first valve adjustment SmileWavy

Good questions. I do remember Bruce Anderson's 911 Performance Handbook saying he pays more attention to one test than another. And I think it's a bit of leakdown with good compression does not mean the death rattle is present. I have the book at home so if I remember I can check tonight.

Yes on holding the crank. If you take the plugs out it will spin easily with air pressure applied to a single cylinder.

The upper valve assembly is oiled. Rockers go up and down fast and oil will be popped upward and also slung upward by the cam lobes. They seal exactly like the lowers valve covers.

Cover gasket covers the spark plug hole mating surface to the engine.

Sugarwood, I am going to say this in the nicest way possible:

Quit being such a spaz! Get in there and poke around. You will not hurt anything, as long as you proceed with a modicum of caution. I went from knowing nothing to dropping my engine multiple times. Just grab someone from your PCA region and have at it. Really, the more you keep thinking, the more you are freaking yourself out. You will be fine. I promise.

Now get out to that garage and make us all proud. :)