GST APPLICABILITY FOR E-COMMERCE PARTICIPANTS

I require experts guidance in the following scenario -

My queries are for E- COMMERCE Participants...

i know tht e commerce participants are required get GSTN but my doubts & queries r as follows-

1. Does E COMMERCE Participants who sell Flipkart or Amazon Gift Voucher *required to PAY Gst to E-Commerce Operator & required to collect GST from end user* ? if yes, at what rate ?

Pls Specify the rate and detailed procedure for filling GST Returns and At what rate GST is to be collected , if applicable .