Re:compression cycles: testing compression in diesels an injector is removed, the fuel bypassed and the engine started.
In gas engines all plugs are removed. I used 5 compression strokes to get the compression reading. You will get to a point that the reading no longer climbs, but generally 5 is close enough for a realistic reading.
You will not ever get a compression reading of cylinder pressure during combustion, peak cylinder pressure, without special test equipement. Under load the cylinder pressure could be 1,500PSI.