Masbooq and Laahiq

Q: A person I know came with me to the Friday prayers. He is not very knowledgeable in Fiqh like myself and we are both non-Aalims. I got out and my companion went to park, but time was running short already, so I managed to find a space, but wasn't sure whether my companion got there on-time. Anyway, I prayed and finished the namaaz. When I got towards the back row I noticed my companion, he pulled me to the side and he was concerned if his prayer was valid, he explained to me the following situation: He came and the Jamaat rose for the 2nd rak'ah, he joined them in the 2nd rak'ah. So when they went into Tashahhud and my companion got up before the Imaam made tasleem, either out of forgetfulness or ignorance, and he quickly managed to finish his final rak'ah and apparently still managed to say the tasleem with the Imaam. He didn't do two prostrations of forgetfulness either. If he neglected to say the Tashahhud out of ignorance as well, would that affect the verdict? What is the verdict anyway?

Q: If you join the jamaat in the last rakaat while the imaam is in tashahud, is your salaat valid or is it preferable to read alone?

Q: If I join Zuhr Salaah behind the Imaam after 3 rakaats, what is the correct procedure to join and complete the Salaah? What should I recite after standing up after the Imaam has made salaam? Surah Fatiha only ? Surah Fatiha and a Surah?

Q:

1. If I miss the first rakaat of jammat after the Imam makes salaam, when I stand to complete the salaah do I read Surah Fatiha or first the thanaa then Surah Fatiha?

2. If I join the Imaam few minutes after he says takbeer, do I still read my thanaa or just lift my hands an keep quite?

Q: A person arrives late to the masjid and misses a number of rakats with the imam. When the imam says salam, he thus has a number of extra rakaat to make up. But he doesn't remember how many. In order to find out, may he pray slowly and see how many extra rakaats the people around him do, since they joined the prayer at the same time as him?

Q: If a person misses the first two rakaats of faradh namaaz, the Imam Saheb will recite only Surah Faatiha in the last two Rakats (which the person has attended), should he (the person) recite only Surah Fatihah in his last two rakaats?

Q: In maghrib I missed 2 rakaats and joined the 3rd rakat, how should I complete the two rakaats?

Q:

1. If the Imaam is in ruku, does one have to first tie the hands and stand in order to get the rakaat, or does going directly into ruku after takbeer suffice?
2. If one makes takbeer and while going into the sitting posture the imaam makes one salaam, can one still join the salaah?
3. If one has to complete missed rakaats in jamaat: In the final sitting, does one read attahiyat, durood as well as the dua, or just stop after reciting the shahadah?

Q: If the Imaam makes sajdah sahw, what should a latecomer do if he sees the Imaam making taslim but then does sajdah sahw? Should he also make salaam and sajdah sahw, or should make sajdah sahw without Salaam?

Q: When should the masbooq (latecomer) stand up to complete his missed rakaats? Should he stand up after the Imaam has made one salaam or should he wait until the Imaam has completed both salaams?