the best way to check is taking a mechanic with you who will do everything on your behalf, a layman cant check the technical specification and conditions of the car, so pls dont even try it. and secondly you can check the gear shifting, and engine health by driving the car, the engine response will very clearly tell you the condition of the car, the RMP drop is normal as reborn got hydraulic power steering pump you when you use power steering the RMP drops little bit and then come back to normal.
so take the mechanic
and ask him to check the suspension, engine, body paint , meter temper, unusual sounds etc .