Omega newcomer with questions

Hello dear Omega friends, I’ve been proud owner of an Opel Omega B 2.5 V6 (Benzin) with automatic gearbox Bj. 11.1994 and super satisfied. My father got the Omega Facelift and I’ve been allowed to have the old one a few questions about the car anyway: 1.) He has about 220.000km down and after the start the engine rattles for about 5 seconds, but what is immediately gone and only appearance when the engine is cold. Has jmd experience with what that could be ?! 2.) a consumption of 13-15l p/100km normal ?(95% city) is of course with speedy driving “the bad S-button…” 3.) off and on when I wait at a traffic light, “jmd” quite easily “jumps” and the car feels uneasy. is only 2-3 times for short time (10min) occurred. Does the maximum of my driving be quite happy yet again. 4.) he certainly has not seen a highway for 2 years. I would like to free it properly (evtl sings of consumption). If I’d like normal? If I’d like to be happy about a good time.