And please don't be fuckheads when you come over here, watch out for traffic, watch out for the trams: so many foreigners get hit or run over by trams. Watch out for bikes as well.Ooh and Bussess and taxis will also drive over tram lanes if they can.
If you are smart you will travel by tram but DON'T buy a 1 hour card in the tram, this will cost you like 2,60 I don't  know how long you are going but a 96-hour chip card is just 20 euros, and that is unlimited traveling in those 96 hours.
For coffeeshops just ask the most stoner looking local, there are tons of coffeeshops in Amsterdam and they usually have the same stock.
Also Dutch weed has far higher THC contents then American weed, so be wary of that.
And about drugs becoming illegal to tourists: higher concentrations of THC and drug tourism have challenged the current policy and led to a re-examination of the current approach; for eg. ban of all sales of cannabis to tourists in coffee shops from end of 2011. Each coffee shop will, from 2012, operate like a private club with some 1,000 to 1,500 members. In order to qualify for a membership card, applicants must be adult Dutch citizens, membership will only be allowed in one club.
And again watch out for these things, they go faster then you think: