Web 2.0: Amateur Questions

good day,
Tell me, please, what is the order of the cost of the web 2.0 engine?
in the future it will be necessary for a collective blog site.
Are there any ready-made engines? Do you need to create it yourself?

to make it clearer, I will explain. need to:

1. so that the view and editorial functionality (tag cloud, interface, etc.) is like a habr
2. as well as here, the first page of the site (and possibly sections) was given to the card-mind. accordingly, you need everything related to karma.
')
do not judge strictly for amateurish approach. enterprise is more than understanding the kitchen itself. it's just a matter of time. here on a habr much is pleasant.
Thanks in advance for your advice.