PaulS:
Where can I find info about "Hardware features" like the internal resistor, i guess it is not the only hardware feature on the board?
Start here: http://arduino.cc/en/Main/Hardware
Pick whichever board you have, and read all the details, even if you don't think you will use them (yet).
I still don't quite believe this but the documentation for 1.0 sounds like the pullups are not active for pinMode(INPUT). This would break a lot of my pinMode() - Arduino Reference
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