I just recently bought a 2000 chevy impala that used to be an old cop car and I can't figure out how to set the clock!

Hi , my name is Bridget... I just recently bought a 2000 chevy impala that used to be an old cop car from an auto recycling company. My radio model came with a radio but doesn't have a tape deck at all, and so doesn't have any "set" or "memory" buttons as far as I can tell (but in all honesty I maybe I am just not seeing them? I don't know...) and so I can't figure out how the hell to set/change the clock. My car just has a power knob that you push to turn the radio on/off and turn for volume, then has a knob below that to push to change the display to either show the clock time or the current radio station and switch between FM1 and FM2 for preset radio stations, 6 buttons you can use to preset radio stations, seek buttons, and lastly an audio button that controls fade, balance, bass and treble. HOW THE HELL DO I SET MY CLOCK??? Also, I was wondering, I noticed that the dash display does not have an RPM display, just a gas gauge, speedometer, and temp gauge. Is this normal? Was just wondering because I am kind of concerned that without this I won't notice if my transmission is messing up since I won't be able to see if the RPM is jumping when the car is shifting into geard while driving. Lastly was just curious if I need to use a specific type of oil in the car when I change it and do I need to use a higher octane gas like 89 or above or is 87 (regular) ok to use in an old cop car? Sorry for all the questions, but the place I bought it from did not include a manual with the car and so I guess I am just a little lost and want to make sure I take the right steps to properly maintain and take car of this vehicle... Because so far I love it, I got a great deal (only 3000), its my first car, and I just want it to last (the engine is BAD ASS btw, definitely love going fast in this car. Oh, and would you possibly know if there are any parts that are likely to go out/need to be replaced more often with this model? Just wanted to know that because it is an old cop car after all and I figure some parts may vary and I would like to stock up on these parts through the Auto recycling place where I bought the car from since they have other old cop cars for sale there and I'm assuming it would be cheaper to buy back up parts through them. Whew, sorry for this huge ass message, I'm just really into cars, really into this car, and want to know as much as possible about making sure I keep this car for as long as I can.