Minimal Internet usage on an Android phone I am considering buying an Android phone and hence the question about Internet usage. How much Internet bandwidth can I expect to use if I want to enable syncing of contacts, calendar, email, etc. (assume e.g. I receive 10 short textual emails per day) I am going to need? 

Is it possible to automatically connect to WPA protected Wifi's, and do all the syncing only when Wifi is available (hence not use 3G internet at all)?

I will use it in a free country (UK atm)
Depends entirely on how many contacts you have, how often they change, how often you set it to sync, etc.  Paying for data as you go is generally a bad idea with an Android phone, they use a lot.

You should be able to shut off 3G though (probably dependent on the phone) and just use WiFi.  Although, it might be more difficult to prevent it from using 2G data.  Some phones let you use WiFi while the phone is in Airplane mode, which would shut off both 3G and 2G.  Android has the ability to store WiFi credentials and connect automatically.