Stock market gains from futures & options

Following doubts are there regarding tax rules for share market profit/loss:

1. Gain from F&O will be capital gain or business income ?
   1. If it is to be treated as capital gain then how the STT and other taxes are taken care
   2. If it is treated as Business income then how the STT and other taxes are taken care and whether the losses can be carried forward
2. How to treat commodity and currency market profit/loss ?
3. How the tax on above two would be calculated for a person with no other income?
4. Whether tax exemption of first 2 lakhs is applicable or some flat tax rate (15%) is applicable.

Please clarify