Good day please I got admission to u.k for my masters please I have the following questions:

1. I want to apply dependant visa for my wife, how much do i need to have in my account for 28days? After printing out the bank statement and the online form where do I submit the form? must make use of agents? I want my wife to do it herself because I heard the agent will collect his commission for the processing
2. How many days does it take to get my visa from the Embassy? my interview will be coming up on 30th of DEC 2015 and my resumption date is 11th of Jan 2016 and last enrolment date is 25th of January 2016.
3. Will I be able to meet up with the 11th of January enrolment date?

Thanks