unless the goods are published in CETA as exempted or zero rated its not exempted goods,
export under rule 18 or 19 ensures the placement of goods out of indian territory and hence the excise duty is not charable but its taxable if placed within india, for transitional movement the procedcure of ARE-1 is followed, to ensure that goods has been placed in real out of indian territory.
regarding service tax, as the services are not "goods to be cleared" so the sealing and despatch with inditity marks is not possible, hence the payment procedure is benchmark for export of services, if services are exported out of indian teritory and payment is received in convertible foreign exchange, then such services can not be taxed with service tax as service tax has its geographical limits within indian terrritory (excluding J&K).