GST MECHANISM FOR E-COM PARTICPANTS

Hi Experts,
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 collect GST from end user ? if yes, at what rate ?

2. Does a Particiants whose TDS deducted u/s 194O , required to collect and pay GST ??

Pls Specify the rate and detailed procedure in each scenario.