procedure for transporting material-interstate- on works contract

hai We are registered in kerala- works contract- recently received a work at chennai- (1) please let us know what are all the documents to be handed over to the transporter/lorry driver/truck driver- while transporting material from thiruvananthapuram- to chennai work site( being a registered dealer from kerala- trivandrum- we have to sent materials from our factory to the work site- DC with e-way bill is enough or tax invoice is required( since this is a works contract- we cannot raise tax invoice for each and every supply of materials- since after supply and fixing- client has to certify the product then only we can raise tax invoice) (2) whether we should get registration in tamilnadu for completing the contract- note: currently we don't have any other work at tamilnadu or we don't have fixed establishment in tamilnadu- nor to have. (3)whether the advance ruling no.KAR ADRG 63/2021 dt. 8-11-2021 applicable in tamilnadu??? since one of JC had told that each state should have separate AAR on this!! if so then what is the purpose of GST??? Awaiting your advice/reply on the above matters Thanks&REgards GFABFSPL