Works contract reverse charge_valuation,abatement&procedures

What are conditions for work/Job to liable for body corporate to pay reverse charge on services availed on works contract.

Is there any abatement for works contract under RCM, or valuation under simple method.i.e. itself the abatement or not.

Please also mention the works contract not liable for reverse charge.

Is there any condition such as labour service should be provided in premises of body corporte for liablity to pay RC on works contract.

Please consider a instance of vehicle maintenance at car workshop,  where there is material purchase & labour service not at the premises of Body corporate.Will company be liable to pay reverse or not.On the ground that no labour service in the premises of company.Can company consider it simply as service inovice and pay TDS if it exceeds the specified limit.

Thanks & Regards in advance.