when i exchange BITCOIN in Coinbase, Circle, Bitstamp, Kraken, Bitfinex, do i have to have an account there with my bank details or to link a card number to them so i receive the dollars? i am from europe, i don't know if they accept to do bussiness with me.
Coinbase and Circle I believe are more based on US. You will want to find one for your region. I'm sure someone will post a good on for Europe.
But most likely you will need to use a checking account to link to the exchange. Yes they will know who you are.
There are some options such as localbitcoin's for those that for some reason don't want to be known, but it has higher fee's and risks.