Treatment of closing stock before gst gets effective

I am into Business of Industrial Sewing Machines & Spare Parts and accessories.

1. I want to know what is the tax treatment of Closing Stock on 30.06.2017 - the last day before GST gets effective?Are we required to pay the tax on closing stock in advance before GST comes into effect or after the implementation of GST?

2. Also do we need to show the complete list of items of Closing Stock { in my case, shall i need to disclose the entire items in closing stock of all the spare parts or is it enough if we provide the amount of closing stock? }

3. Also whether there will be manual Invoices or Printed Invoices after GST implementation?

Kindly help.