You should read all what you can read as there isn’t any silence in prayer where you don’t say a thing.

When I join the congregation late then in the last Tashahud with the congregation should I only read Attahiyat or Durood-e-Ibrahim should also be read? And when I join the congregation from 4th Rakah, and get up to continue my prayer from the 2nd Rakah, then in the 2nd Rakah should I read a Surah after reading Surah Al-Fatihah or not?