Upvote:-1
I dont know about the visa, but at AMS the train into the central station takes about 10mins and you can walk to everything from there. If your stop over is later in the evening walking around the red light area can be a scary experience and i would not advise it alone. On the other hand, have a look in the daylight hours. Eat poffertjes, smoke a joint, go and check out some art at one of the museums or take a canal boat trip then hurry back to the airport.
In an 8 hour layover, from the time you step off the plane to the time you are walking out Central station should be 1 hour on a good day, 2 on a bad day. you will need to be back at AMS about 2:30hrs before your flight, so if you are lucky, out of that 8 hours if you have the visa in check you might have 4 of it to wander around the city.