New unit or division of existing company, how?? process?

In company  law there is no specific requirement except sign board and option of appointing separate statutory auditor for the branch, if necessary, and maintenance of books of account at registered office.

For setting up second unit at different location you have to take care of registrations under other laws as may be applicable in your case including filing of IEM, Factories Act, PF/ESI/Contract Labour Act etc. etc. 

You have to prepare single consolidated Balance Sheet for both units and file single IT return since PAN will be same.