Masbooq forgetfully making salaam with the Imaam

Q: I missed one rakaat of jamaat salaah. I would like to know if sajdah-e-sahw should be made or not in the following cases after the Imaam made salaam to end the salaah:

1. I made one salaam on the right and then stood up to complete the missed rakaat

2. I made both salaams on the right and left and immediately stood up to complete the missed rakaat

3. I made both salaams and sat in the same position, and after one minute I stood up to complete the missed rakaat.

Passing away from coronavirus

Q: I have heard from someone that if one passes away because of cancer, they pass away as a Shaheed (that is they gain martyrdom). They also have said that if one passes away from the corona virus and any other such virus then they also pass away as a Shaheed. Is there any truth to these statements?