Phantasmatic nature of identity

The following text describes the artwork below titled Easy for Who to Say by lorna simpson.

1. Does "we fill with signifiers which communicate with one another" mean "we fill with signifiers by which we communicate with one another" or "we fill with signifiers which these signifiers communicate with one another"?

2. Does "and performs the phantasmatic nature of identity per se, including race" mean "and represents the imaginary nature of identity, including race"?

3. Does "which" refer to "the phantasmatic nature of identity" or "race"?

Description:

The work makes me think of Lacan’s dictum that there is a void at the heart of the subject that we fill with signifiers which communicate with one another rather than express our intimate sense of being. In exposing these signifiers in the guise of vowels that bar access to the narcissistic register of the face and eye contact, Simpson’s work goes beyond simply pointing to the social conditions which interpellate blackness as inferior and performs the phantasmatic nature of identity per se, including race, which, while being over-determined as a signifier, is nonetheless a filling out of a loss that cannot be represented, i.e. the subject’s traumatic relation to death.

(https://lsimpsonstudio.com/photographic-works/1989 of image)