Really, there is no standard guide to assist you in these matters.
Whatever improvements that are needed, will totally depend upon current practices in your own organisation, and at each manufacturing unit in different parts of the country. You have to study these current practices and identify the areas in which improvements need to be made, and how best to make these. The latter task needs a little more experience than you seem to have.
What you can do, however, through proper study and subsequent meetings with other HR managers in other units in the same geographical area and/or industry, at least identify the weak points or gaps in your own practices, draft out possible remedies, and discuss these with your superiors before putting these down in writing in a formal report.
Nobody can give you the answers. You have to find them yourself.
Use the same approach for the legal requirements that must be met. Ask the HR personnel in other units that you meet which acts/statutes they have to comply with (follow). Then study those acts/statutes and ascertain which are not being followed by your own manufacturing units. Then bring these up with your superiors and make a formal report.
Honestly, CiteHR members can generally guide you, but they cannot do what you yourself should be doing. Pull up your socks and start working!
Jeroo