Re: following imam 1) Is my salah nullified if the imam gets up from ruku, whilst I didnt reach ruku because of trying to complete Fatihah (based on the view that it's fardh to recite it)? 2) I bow etc once the imam has, but what about salam? Do we do salam after he has or simultaneously?

Ustadh AbdulAziz al-Haqqan

Your Salah is invalid, but even on the view that reciting the Fatiha is a Fard, you can just say "Allahu Akbar" and follow the Imam. As for as-Salam, then it is after he finishes.