Service tax registration

We are a small software development partnership firm and develop only customized software for clients.
Last year our sales was about Rs. 15 Lakhs and of this 95% of our sales was exports. Only about Rs. 1 Lakh was for domestic clients.
This year we have done about Rs. 15 Lakhs from Apr'09 to August'09. 100% of this is exports. We will doing only about Rs. 1 lakh of domestic sales in this year.

Queries:
1. We are not registered under service tax. Do we need to register our firm for service tax considering that our local sales is within limit of Rs. 10 Lakhs.
2. If yes, do we need to pay service tax on our export sales?
3. If registered, do we need to pay service tax on our domestic sales?
4. What is the rate of service tax for customized software development?
5. Will we need to pay service tax and VAT on domestic sales?
6. We do not want to claim any rebate of service tax on inputs. Will be still need to register?