Was the Yastreb the Soviet/Russian equivalent of the Snark cruise missile? It looks so similar to the Snark layout wise
No, however it should be noted, that you are not that far from the truth. Initially, it started as a project of intercontinental supersonic cruise missile. When it became apparent that such weapon systems are impractical (not only ICBM were much more capable, but USSR also was rather pessimistic about cruise missile chances to penetrate NORAD), the project was re-purposed toward long-range reconnaissance drone.
The Tu-123 was supersonic partially re-usable recon drone. It was launched from mobile platform using a cluster of solid rocket boosters. After launch, the drone was tracked by the land-based mobile radar, which also was used to send guidance command during the initial and final stage of flight. The flight was commenced on the 20-22 km altitude, to the distance of up to 3000 km, mostly under pre-programmed inertial guidance. After the reconnaissance mission was finished (she was equipped with numerous photo cameras), the drone returned to the launch point, and its equipment section with cameras and film jettisoned from the rest of the craft, and landed on parachute. The equipment section could then be re-used, but the rest of the drone - not.
The Tu-123 was supposed to be used to make deep-penetration recon flights through NATO airspace in case of war. As far as I know, it wasn't used in actual operations.
The semi-reusable version (i.e. it could be re-used, but only after repair and maintenance) was developed as Tu-139 "Yastreb-2", but remained only as a prototype, because more modern recon drones were in development.