Hi, welcome to the board
First, your pH is way too low for a SW tank, therefore, I don't believe the value, I've seen tap water with a pH of 7. Yours is not 7.0. Trust me, it's just not. If you have cleaner shrimp in the tank surviving, your pH is fine enough.
Tap water is not the best, but many successful people here use it. Again, not likey your problem.
what kind of salt your using is important, maybe check it and report back.
Ammonia is too high if you can read it, so yes, you need to find the dead fish. Sucks, I know, but you gotta get it out. The tank is too small to support natural decomposition.
I agree with Canadian, dripping for an hour is not required, I float to match temp, dump them in.
Salifert kits are good. Elos kits are good.
Specific gravity is too low for a reef, it should be 1.026. But, at this point, you're just trying to keep fish alive, 1.022 will not be harmful to them.
Now wait until you stabilize things a bit, do a water change to get rid of ammonia, next time you get one fish only, acclimate as described by Canadian, and see if you have better luck. If someone here has offered to test your water, take them up on it, a third opinion is great.