3 more questions:
1) if the car is in city mode, can i still change the gears manually if i need to? especially from 1 to 2? would the mode change?
Yes, but it will exit "City" mode when you do, except for when going slowly in "City" in 2nd gear, manually changing to 1st doesn't take you out of "City" (sometimes!)
Edit: I think some of the later systems may allow manual changes when in "City" without taking it out of "City mode".
2) if the car is in manual mode, will the gears change automatically (up and down) if i dont actually do it myself?
In manual mode it will change down on its own when you slow down. How many gears and when will depend on how hard you brake. ie if you suddenly stamp on the brakes at Motorway speeds it will instantly change down one or two gears. However, if you are in 5th and just coast to slow down it will be going quite slowly before it changes down.
It will allways select 1st gear when you come to a stop.
In manual mode it will only change up on its own when you get close to the rev-limit. It doesn't hit the rev-limit, it just changes up.
3) there seems to be a cracking sort of sound when i change gears, usually when going down. especially from 2 to 1. is that normal?
As long as it is a "clack" sound and not a grauncing gear sound, then yes it is ok. However, there is a big gep between 1st & 2nd gear ratios, so don't select 1st until the revs in 2nd are close to 1000rpm.