what is the turnover of the Indian company ?

2) if the turnover of the company is over 20 lakhs it needs GST registration

3) PLANS AND DRAWINGS FOR ARCHITECTURAL,ENGINEERING,INDUSTRIAL, COMMERCIAL,TOPOGRAPHICAL OR SIMILAR PURPOSES,BEING ORIGINALS DRAWN BY HAND; HANDWRITTEN TEXTS; PHOTOGRAPHIC REPRODUCTIONS N SENSITISED PAPER AND CARBON COPIES OF THE FOREGOING HSN code is 49060000

4) you have to raise GST on the invoice amount

5) GST would be applicable on Plans and drawings on architectural, engineering, industrial, commercial, topographical or similar purposes, being originals drawn by hand; hand-written texts; photographic reproductions on sensitised paper and carbon copies of the foregoing fixed by GST council at the introduction of GST in July, 2017 is 12%

Since turnover of company is below 19 lakhs you do not require GST registration

You don't have to add GST tax on the invoice

Now, my question is, what documents are needed to raise that invoice?

The basis on which you make this invoice shall be the document for this.

If there is an agreement between you two and if you comply with the conditions of agreement, then that is the basis of invoice.

As the payment will be in USD on my sister current account, should I add any tax / vat / gst percentage on the current invoiced amount? If yes, what may be the percentage?

For accounting purpose, your sister's company shall be following the current tax system added to the invoices, the same shall be applicable for this too.

There is no transaction till now of that company. Also the engineering drawings are not drawn by hand. It is in computerised software named Autocad. The job is from New Zealand. And they will pay that in USD in my account.

Shall I have to add 12% GST for this?

The percentage of GST to be charged on this shall be clarified from any local auditor/CA