1. Joint account with parents cannot be shown as POF; funds will have to be in your name. Joint account with accompanying spouse are accepted as POF but not with parents. So, if the balance letter and/or statements from the bank does not mention your father's name, then you are good to go, but if they do, then would suggest you to remove your father as a joint account holder and then get the letters and/or statements from the bank.
2. If the above account has more than enough funds, then you necessarily need not submit salary account details. But, if you want to, you can.
3. Ideally, the letter from the bank should mention details of all your financial assets and liabilities with the bank. So if the bank is willing to provide those information, then get it on the letter.