Service Tax on Software Export Firm

Dear Club Members,

Please help me understand some points regarding service tax.

i own a web development firm as sole proprietor.  if i register under Software Technology Park India, and make my unit 100% software export unit (because we do application development and my client base is outside of India) still i have to pay service tax?

After registering as Software Export Unit is there any excise duty imposed?

Thanks.

Gurinder Singh