Dear can please answer my question:

I am an Indian citizen, work here in Qatar from last. I would like to bring my wife and kid in a family visit visa. I have some questions-
1. Is there a minimum Basic Salary to sponsoring family visit visa? If yes, what is the minimum Basic Salary?
2. I heard that we need to submit three months bank account statement to apply for a family visit visa. Is that true?
3. What are the documents that need to apply for a family visit visa? What is the fee for that? How long it takes to get the visa?
4. How long this visa exists? Can we extend the family visa? If we can, do we need to pay for every month extra? How much?

Thanks in advance
Roshan