TDS regarding GST ACT

1. No...

2. It's basics of the Law. No need or required Amendment...

As per SOP on TDS release on CBEC site:

No TDS is to be deducted

1.Where the payment relates to a tax invoice that has been issued
before 01.10.2018.
2. Where any amount was paid in advance prior to 01.10.2018 and
the tax invoice has been issued on or after 01.10.18, to the extent
of advance payment made before 01.10.2018.

Hence if you have already issued invoice before 1.10.18 then NO TDS has to be ded. on its payment made after 1.10.18