Income by providing service to usa from india as individual

If you are resident then your income is chargeable to tax by virtue of S. 9

You can claim deduction of expenses you incurrred for providing this service to your client, once you have computed the income , you may claim deduction under Chapter VI A [like 80C etc.]

You are not liable to Service tax, but Income tax is still applicable.

Since you are receiving the remenuration in India hence it is taxable ireespective of your resident status...If you are receiving the remenuration outside India and then it is repatriate to India then also it will be taxable in India as long as you are resident (status) in India...(refer section 5 for details)