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 
you can't really get exact number of bitcoin users, it's not possible i guess. for rough ideas check out the links posted by Anillos2. This is the beauty of Bitcoin. You can never know.
Different wallet addresses does not mean different people, so it would be impossible to link transaction volume or wallet addresses to the number of people using Bitcoin. And I like it.