payment to foreign entity

Dear all,

A co. in india is making payment for Rig Hire charges, to a US firm.What is the rate of TDS.( withholding Tax ). Within how many days TDS should be deposited with Gov. of India.

Is there any liability under the service tax is also there.

Can we dalay the entry  of Invoice for Rig hire charges in our books till the date of actual payment to delay the TDS payment. Please advice.