Yes, es is the impersonal subject (in nominative), and the real subject is in dative here (as we ask for the condition / state to which it is subjected, and German uses for this in a few instances the dative).

Wie geht es ihm? – Ihm geht es gut. / Ihm ist bitterkalt. / etc.
but: Er ist krank. / Er ist in Ordnung. / etc.

Nothing.

The dative case is not only used for receiving things.

Here, it's used for the experiencer, the person who feels a particular way, who is doing well or badly or in some other way.

Is that an actual question or was that your answer and you're asking why it's incorrect?

The experiencer is in the dative case for the es geht construction relating to health.

Wie geht es dir? "How are you?"

Wie geht es diesem Mann? "How is this man doing?"

Es geht ihm gut. "He is doing well."