Does anyone know how many people is using bitcoin very often and how many are "weekends" users, with weekend users I meant people who bought it and hold it for a long time 
We never know who sold it or hold it! That's the whole point behind Bitcoin
But you can see who downloaded Bitcoin client and average growth
http://www.bitcoinpulse.com/#/chart/btc_client/num_client_downloads
Number of wallet users by time:
https://blockchain.info/charts/my-wallet-n-users
Number of transactions per day by time:
https://blockchain.info/charts/n-transactions
Thanks a lot, This is the info I was looking for...