1. Balance sheet 2. Profit & Loss a/c 3. copy of PAN (for PAN no, date of birth) 4. Correct address 5. ITO ward (you can find out this from income tax site) 6. Type of form (visit above mentioned link) 7. Bank statement 8. Computation of income and income tax 9. CBS bank a/c no (in case of refund, amount will directly be credited to this a/c)
Income tax site provide the free utility so you may not require to buy any software. However if you find it tedious you can buy software sold by Taxman. There are many software available in the market. You can choose any of them.