Q 1)What should be steps to follow to petition a step child who is 11 years old when US citizen already sponsored his wife on CR1 visa and she...

I agree with my colleague .... it could be that her passport will be expiring on that date.

My friend would like to file her cap exempt H1B visa. She had approved H1B back in 2015. What should be the next steps.

Keep in mind that it is not 'her' H-1B .... only an employer can file.

What is the H1B to permanent residency process?

After the H-1B is approved, the employer will have to file a PERM application with the Department of Labor

The hotel quarantine by Canadian government? Does it apply to me if i'm just heading to the POE to apply for a new TN visa?

Call the CBP post that you plan to use to enter the US.

I don't quite understand what you mean by "keep stamp"

Form I-539?

No, it wouldn't look bad during this time of COVID-19 ... make sure that you include proof that there are no flights to your homeland.

Currently working on EAD. Plan to get stamping outside USA for H1B. When is i considered on H1 Status?

Let me guess, you have an OPT EAD. Normally employers file for a change-of-status from F to H-1B

How often and quick does a K3 get granted if I apply from abroad for a marriage green card so I can live with my spouse in US ?

I agree with my colleagues ... the O-1 is the fastest way to go.

I agree with Mr. Behar .... file on paper, not online.