1. First one is input service distributor. they should take input service registration from service tax department 2. There is no one to one relation .even telephone of junior staff and to top officer bill , both can e availed equally . 3. As per general rule Cenvat can only be taken at place of registration , therefore when Invoices are charged both at Ho & Factory , it is advisable to opt for ISD registration to avail of . 4. Cenvat can be distributed as per rule 9 and separate return is to be filed by ISD in ST-3