I am a new driver and I know very little about mechanics. Could somebody help me with my silly questions.

My 92 190E speedometer pointer vibrates at speed below 40. What does a vibrating speedometer mean?

There is a indicator turned on whenever I start my engine. The indicator looks like a tank with some water ripple. What does it indicates?

There are 2 tanks on the left side of the engine when I am standing in front of the car. One of them is a small 'brown' tank, and one of them is a big white tank. What are they and what I should fill in?

There is a position, that looks like a <-P->, at the leftmost position of the headlight switch. What is it?

Is there anyone kind enough to tell me where can I get a owner's manual for this car, as it is much more complicated than my previous cars. (I owned a Mazda and a Kawasaki)

Cheers,
Barry