Meet the locals
The locals, Amsterdammers, have a reputation for telling people off. Deep down inside an Amsterdammer is an anarchist. Authorities don't get the respect they want to have. Ambitious plans get ridiculed or are met with fierce opposition. The locals want change, but not on their own turf.
When a local adresses you with "Hee, wat nou?" (Hey, what's up?), think about Robert De Niro's famous scene in Taxi Driver. The local assumes that you have made a stupid mistake and wants to pick a verbal fight which you will loose, since he is more fluent in blasphemy and scatology in English than you are likely to be (or in any other language for that matter. The Dutch just love swearing, and Amsterdammers are the undisputed champions).
Most of the Amsterdam inhabitants were not born there. They come from all over the country, the whole wide world for that matter. Most of them adapt quickly to their new environment, and tend to be even more cynical and straight forward than the born and bred locals.
Amsterdammers as a whole don't care much for the millions of tourists who visit their city. They are friendly enough to help you out when you get lost or indulge into some the typical stupid things tourists are likely to do. However, there is no excuse for riding your bike in a leisurely manner.
English is the unofficial second language in the city, so no problems there. It is possible to become fairly good friends with a local (buying one a beer is a good way to break the ice). Mentioning you intend to visit Rotterdam is best avoided.