Answer
(Fatwa: 1602/L=454/tl=1431)
(1) If he intends to travel to a journey of 77.25 km [or more], it will be necessary for him to offer qasr salah.
(2) After crossing the area of town or village, the rulings of musafir (traveller) will be in force and qasr will be wajib on him thereafter.
(3) During the journey too, one can offer salah with jama’ah. If the imam is muqim (one who is residing at his own place) and the musafir is praying behind him, the musafir will have to offer the salah of four rakah as four. If the musafir offered qasr salah, he fulfilled the obligation. If after offering salah, he finds jama’ah going on, it is not necessary for him to join the jama’ah. However, if that salah is of Zuhar or Isha he can join it, if he wishes, with the intention of nafl.
(4) It is proved to recite only tashahhud in the first qa’dah (sitting) of four rakah salah. Hence, it is not right to exceed it. The ruling regarding the case you mentioned is that the masbuq should recite tashahhud in slow pace until Imam finishes the salah with salam.
(5) It is forbidden to offer nafl salah from the dawn to sunrise and after Asr salah till sunset, but it is not prohibited to offer fardh or qaza salah.
(6) What do you mean by sajdah? Explain it and submit the question again.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband