Job work transactions amount

yes. Invoices compulsory. way bill compulsory. 

Corresponding disclosure under GSTR-3B & GSTR-1.

Practically, unless job worker makes payment against invoice to the principal, he would not be eligible for credit u/s 16 of CGST Act. Therefore, suggest job worker to make payments, claim the credit, and include the same as part of valuation for services rendered. However other implications on financial statements needs to be considered.