Yes.
Trusted Substrate exists in two flavours that build on SystemReady counterparts: TrustedSubstrate-IR and TrustedSubstrate-ES:
TrustedSubstrate-IR implementation is built on Trusted Firmware A, OP-TEE, U-Boot and uses Device Tree as hardware description.
TrustedSubstrate-ES implementation is built on EDK2, OP-TEE and uses ACPI as hardware description (main difference with typical datacenter firmware is the presence of OP-TEE). There are discussions to extend U-Boot to offer a full ACPI support in this context.
Currently no.
Only EDK2 has the breadth of ACPI and UEFI implementation to be compliant.
PSA has APIs and a certification process. The scope of the certification does not impose PSA APIs. PSA certification is about quality of implementation verified by (self for level 1, lab for levels 2 and 3). For level 3 certification, hacking attempts are made in addition to some automated verifications.
So TS implements many PSA APIs backends and FF-A interface (which defines a transport mechanism for PSA APIs).