Tax on Professional Services for Non Resident in India

1. TDS / WHT @ 10% on professional fees ( 7.5% rate as a COVID relief measure till 31.03.2021 )

2. GST registration not required.

3. Ensure that your bank account is a domestic saving account ( NOT NRO ). If you are looking to remit funds from India to Abroad, you might have to consult an International Taz Expert and explain your case in detail. As he would guide on DTAA specific to your country and India, Income Tax Act, and TDS u/s 195.

1. In a normal case Company will deduct TDS @ 31. 2%. (However, specific DTAA with the country of your residence needs to be studied, regarding the taxability of the particular service)
2. No one answer to this. As it is import of service for the company, it is liable to RCM. However, you will be covered under the definition of NRTP, you will be liable to get registered and deposit GST in advance.
In my opinion, it's better to get registered as NRTP, file GSTR-5, and later recover the GST in the bill from company, since you have a bank account in India.
3. Read 1 & 2.

For registering GST under NRTP  i would need an establishment address in India, since i will be working virtually there is no address in India.  Can you advice how the GST would be registered without an establishment address ?  

Sorry for the inconvenience. After further study regarding the subject, I noticed the anomaly mentioned by you. NRTP needs to provide an address in India on the GST Portal. However, non resident person providing services is covered under defination of NRTP.
Further you cannot register as non resident service provider, as it is for OIDAR.
So as per my limited study, the service will be taxed on RCM, and you will not be required to register.