Like I said, compression test will determine if the engine is still usable.

Attempted a compression test... Engine cranks fine with all plugs removed, all looked a little wet from coolant but otherwise okay/similar.

Cylinder 1 is still hydrolocking the engine with the compression gauge on and sprays coolant like a whale with plug out while compression checking cyl 3 and 5 which both measure about 190 PSI.

Now what? I mean maybe my arms need to go on a diet but it looks like a bear to check two of the back three cylinders and once I do, say they also test around 190 PSI.

I'm wondering if I need to pull the lower radiator hose to drain the coolant (radiator drain valve may not have been touched since it was new, could be a problem to open it) then keep cranking on the engine till it'* clear of coolant in the wrong places (and how long I'd likely need to crank till I get there), THEN recheck cylinder 1?

Methinks you have a bad upper plenum leak at the EGR tube......

Small leak near your alternator could be coming from the water pump gasket, but I am sure you have a intake manifold leak as well.
Testing the compression is not too hard, remove all of your plugs, and crank it over as Mike suggested, if any coolant is in the cylinders you want to get it out of there ASAP.
Then test the compression of each cylinder, write down your numbers for each one.
Normally you want the engine mildly warm when testing, but you can still get good enough results from a cool test.
You can unscrew the screw for the ICM, that will stop the injectors from firing.
Or pull the fuel pump relay.
Deff be sure to have a full charged battery to do the tests, screw the tester into each cylinder, crank the motor over till you see the needle on the tester stop rising.

After that I'd also do a wet compression test to see if any rings were damaged, to do that get some clean motor oil, and squirt 3 or so drops into each cylinder, then re-test and write the numbers down, then post them all here.

That tester sounds hit or miss, more miss than anything, so you may want to try to find another store to rent one from, or consider buying one, I got one for 40.00 a while back, it is decent.

Innova has one for 23.46 on Amazon, not too bad of a price.

I pulled the lower radiator hose, cranked her a few times to evacuate coolant, then got a good ~ 190 PSI reading on cyl 1. I'm going to bite the bullet and pull it part for upper and lower gaskets.

I am not sure you are understanding how the leaking of the coolant happens, once the gaskets leak, if fluid is pulled into your intake, it gets into the cylinders and hydra-locks them, which can occasionally totally ruin your motor, it has been known to throw a connecting rod through a block, because the coolant/water does not compress.
There is no way you can remove the lower radiator hose, and evacuate any coolant out of the cylinders, it is just not possible.
The only way is to do what was suggested, pull all of the plugs, then try to crank the car over, this is the only way you are going to get the coolant out of the cylinders, if the motor is truly hydra-locked.
If you did remove all of the plugs, then you want to get compression numbers from all cylinders, and compare them, not just a compression number from one cylinder, it is possible one of the other cylinders could have a lot lower compression.
Each cylinder needs to have close to the same compression, I think it can be up to 10% less, but anymore than that and it is possible to have problems with it running right.
190 PSI is higher than I expected your compression to be, if all cylinders are close to that then you have a really good motor.

Those cylinders need to be dry before doing a compression test. With them being wet can hide any leak downs normally seen if they were dry.

Drained all your coolant down, with spark plugs out and throttle at 100% crank engine over for about 20 seconds. This will open the throttle plate all the way allowing the most air into the engine and this also shuts the injectors off. This is called "clear flood mode".
Now, you can conduct your compression test.

I think my mistake was compression testing cyl 1 before cranking it enough to purge all remaining coolant. I hadn't imagined just how much it was sucking in, in such a short period of time after literally running fine.

It wouldn't surprise me that it has high compression given that it was driven lightly for its few 50K mi. but I have no reference... if this gauge is off a bit I have no way to know but all cylinders tested give a consistent ~ 190 reading. If they're wet, considering the plugs were, just coolant coating the cylinder walls, not standing liquid, would that raise compression numbers a bit?

Yes. What you can do is reinstall the plugs, connect the wires and run it for about 15 seconds. This is WITHOUT coolant installed. Remove the plugs and retest.