NEW EDIT #2, SEE BELOW:
Kitchen sink drips from the tap, stops when I turn off hot water shut-off underneath, so I assume the problem is the hot water faucet. I think I know how to repair a faucet with a screw (unscrew to access cartridge and replace it), but when I pried the "H" cap off this one and the metal disk under the "H", there was no screw underneath...just a hole (see photos).
There appears to be nothing obvious inside to unscrew. So, how do I proceed to fix this faucet?
EDIT #2: I give up on removing it from above--I am going to try to remove this from underneath the sink. I'm attaching new photos of what that looks like, and asking for guidance. As you can see, this has been dripping down and rusted out the washer. Do I definitely need a basin wrench to do this, or can I use a socket wrench? What happens when I get this disconnected from underneath?