Thank you for your input Mahendran. So, there is no paarticular amount of sum that I should retain in my account during their application. They are living with me presently and my salary is our sole income. So, I suppose my current income status and expenditure details should suffice.
My wife is a graduate from India and she has done a masters course over here in the UK. If I am right, that should exempt her from the english test.
Thanks again for your input.