Q1.How many magnets it brings?
Q2.how many magnets are inside? Can it hold a Nexus 6P?
I'm not sure how many magnets are inside, but it is really strong. It holds my galaxy s7, which is heavier than the Galaxy S6, just fine.
Q3.Is the plate that goes on phone / case colored? I have a white phone with a clear case and not sure I"d like seeing the square on the back of it.
The plate is black. You will see it