So I was looking at MySource Classic and it does exactly what I want it to do.
So I have a question, does Matrix version have all the features of Classic?
Also is there modules for Matrix like for Classic?
For example, I wanted to buy module for Site Search (search through uploaded documents is necessary for me), Calendar, Visual Template creating? Will Matrix have that or I can buy it? Either one works.
I hope someone can help answer some questions.
Matrix and Classic are quite different, so its not a simple question to answer. 
I'll do my best though:
There are modules for Matrix, including Calendar, Search, LDAP integration, etc. These are commercial modules (same as with Classic). The Search does allow you to index Microsoft Word and PDF documents that are uploaded into the system. There is also a full Calendar module as well.
Matrix does not have the same Visual Template system, as Matrix doesn't work the same way as Classic in this regard. There are various alternatives built-into Matrix including design customisation and paint layouts.
Its best to speak to a Squiz Account Manager (and possibly Implementation Specialist) to discuss your requirements to work out if Matrix will meet your needs. One of the core strengths of Matrix is its potential to scale to very much larger sites than are easily manageable with Classic.
thank you for answering
does matrix support anything besides PostgreSQL?
Do any of them (Classic or Matrix) work with MS SQL?
Matrix can run on PostgreSQL or Oracle (8i/9i/10g). Neither Matrix nor Classic support SQL Server.