Qadha Salaah

Missing a waajib in qadha Salaah

Q: I know that if you miss a waajib in prayer, you must perform sajdah-e-sahw, and if you fail to do so, you should repeat the prayer, so long as its time remains. However, once the time for the prayer is over, the prayer is not to be repeated. What is the status of missing a waajib act in a qada prayer? If you miss a waajib in a qada prayer, and you failed to perform sajdah-e-sahw (or you performed sajdah-e-sahw incorrectly, i.e. you made only one sajdah), do you then have to repeat that qada prayer? Is it merely recommended to repeat that qada prayer or is it waajib to repeat that qada prayer?

Salaah becoming qadha

Q: This morning I was going to wake for fajar and heard the namaz and saw someone else in the bathroom so I closed my eyes and waited. I didn't realise that I fell asleep and when I got back up it was still dark so I rushed to the bathroom to make wudhu. I am a very doubtful person so making wudhu takes some time but I am trying to get better and did it as fast as I could. When I came back I looked outside and it was still a dark blue and there was little  yellow in the far back so I quickly started praying. I didn't think it was that late as fajar happens around 6. I thought it might be 6:30 at the latest but after I prayed 2 sunnats I checked my phone and it was almost 7. So I finished my namaaz. I know it is bad to delay prayer and I didn't mean to. I am so worried I might have prayed in the forbidden time but I remember reading that if you didn't mean to delay fajar prayer you can pray as soon as you remember or wake up so did I do the wrong thing? How do I fix this?