if while driving you need wheel alignment an/or wheel balancing. if it s just while idling it can be a few things like worn motor mounts clogged fuel injectors causing low or ramping rpms
Erratic RPMs while driving or in park could be due to a faulty oxygen sensor. It is also possible that poor gas is being used.
air leek
The spark plug gap can cause the RPMs to fluctuate, while idling. The more probable cause of the fluctuating RPMs is a bad camshaft.
No, that is not normal. Should be around 2500 rpms.
Poor driving habits, poor air intake, improperly adjusted fuel pump, excess operating RPMs.
If by surge you mean the batterys volts drop and the engines rpms drop all the vehicles accessories that are on at the time are wanting to draw more amps then the vehicles alternator has to give. or by surge you mean the rpms increase a little bit and if the heat or A/C is on at the same time the A/C pump or clutch might possibly be going out.
Roughly 800 RPMS while in park and roughly 600 RPMS while in drive or reverse
Bad MAP sensor, throttle position sensor, O2 sensor, many possibility's it would be a good idea to get it down to a repair shop for an exact diagnosis.
If the RPMs in the engine increases and the speed not, the clutch may be worn out, usually it becomes noise at the same time
Have your cold air intake checked out.
a bad idle sensor control valve to start with or your egr valve has a vaccum leak