Service tax on works contract

IN COMPOSITION SCHEME FOR SERVICE TAX ON WORKS CONTRACT, WHETHER

A.INPUT CREDIT ON SERVICES USED IN OUTPUT SERVICES BE AVAILED OR NOT

B.IF WORK WAS SUB CONTRACTED THEN THE SERVICE TAX PAID TO SUB-CONTRACTOR BE AVIALED OR NOT

C.IF SERVICE TAX WAS PAID BY THE SERVICE RECEIVER ON REVERSE CHARGE MECHANISM THEN WHETHER SERVICE TAX PAID CAN BE CLAIMED AGAINST SERVICE TAX PAYABLE ON CONSTRUCTION CONTRACTS ON COMPOSITION SCHEME OR NOT.

PLEASE CLARIFY