It was no longer possible to enter the temple, for it had filled with rubble years ago, but they admired the exterior, as did all the tourists Mr. Kapasi brought there, slowly strolling along each of its sides.
Another sentence -
He plays the piano as does she.
My specific question:
Is the function of as which has been used in the two sentences the same?
In your example sentences as is a conjunction.
As
(conjunction) In the same manner or way that:
Example -
Think as I think.
As a conjunction as introduces a clause that is sometimes inverted. There as mean so or likewise.
He went to military school as did his friend. [= He went to the military school, his friend also went there.]
Your example sentence -
It was no longer possible to enter the temple, for it had filled with rubble years ago, but they admired the exterior, as [did all the tourists] (that) Mr. Kapasi brought there, slowly strolling along each of its sides.
Here as introduces the clause - [did all the tourists]
did means admired here.
But you might be thinking why in that subordinate clause - [did all the tourists] - the subject-verb is inverted.
There are reasons. Firstly it sounds better that way, and secondly it's to keep the antecedent of that - the tourists - close to that-clause - (that) Mr. Kapasi brought there.
Your second sentence -
He plays the piano as does she. [= Both of them play piano]
But the non-inverted version means something different.
He plays the piano as she does. [it might mean the same as above or this - He plays the piano the same way as she plays]
