Hi sat,
I'm not familiar with which documents you need to submit in India and which need to be sent to Sheffield.
You may find this successful example posted by a lady who married her Indian husband helpful
immigration-for-family-members/spouse-v ... 25775.html
My wife applied in Russia and the only thing she took to her biometrics was her passport. Everything else went to Sheffield. If you would like to see the general list of what we sent to Sheffield, to compare with the above example, please see my thread on page 2 of this board..... Spouse Visa For My Russian Wife - Please Help.
immigration-for-family-members/spouse-v ... 26338.html
Not all of the documents we submitted are mandatory or may be necessary for you but comparison of both examples will give you a good idea.
As to priority, we applied with priority and are at day 27 tomorrow since biometrics appointment. I have not received any documents back yet or any correspondence from Sheffield since the documents arrived with them 19 days ago.
Good luck
Simon