Advise on Export of Service

Client business is provideing websolution online to Customers in United States(US) and the payment for the same is credited in the bank account directly from US. There is no other type of service provided by the client.

Query:

How should the structure be designed to effect the export of service? ( like STP / EOU etc.)
Also, Client is not in favour to relocate the place for STP/EOU status, so what other possibilities it can have.
Do they fall in the ambit of service tax?
IEC code would be compulsory I believe.

What other suggestions could be in the favour?