Work permit letter missing for ILR

Hi,
I have recently cleared the Life in Uk test. I am planning to apply for settlement in september.
I have few queries.
1. When i came to Uk for first time, i came with Work permit with Work permit letter from UK BA. But unfurtunately i not finding this documents. Is this Work permit letter is required to submit if yes, is there any alternatives as i am lost that paper.
2. I am planning to apply in Birmingham, Any updates how is that center.
3. I am also applying for my wife and son for setllemement. Could you please let me know the documents required for them to apply. I have Bank statement for both me and my wife names in bank statements. Also i have rented agreement where both names are mentioned. Apart from this i do not have any documents for my wife . Please suggest what extra i need for my wife to show the address proof.
4. One more thing, Recently i move the salary account from HSBC to Halifax. I have been with HSBC from last 5 years, but last 2 monthhs i join Halifax and move my salary to this Bank. Is thi going to have any issue while applying ILR.

Please help me to resolve these issues.

Thanks
Supi

Please continue in previous thread.