I have already got 4 coats of paint, now I'm going to make final one and then clear. My questions for more experienced paiters are:
1. Should last coat of paint be sanded wet (1000,1500,2000) and polished or maybe only sanded? (I'm going to put clear on it)
2. Should last coat be perfectly flat? (I have little "hills" - will they dissapear after puting clear?)
correct me if i'm wrong...

but i don't think you want your paint that smooth since the clear has to stick to it, it wont' matter if you polish the paint since you'll polish the clear and that will make it look good.

as for the hills...those will show up through the clear.
give it a rough sand down with 400 grit paper to get rid of those "hills" one final thin coat of color, then you can lacquer.