Following other Mazhabs in Salaah

Imaam performs 2 rakaat of witr followed by a single rakaat

Q: The mosque I am going the imaam makes the witr as 2 rakaat followed by 1 rakaat in which he makes qunut after the ruku whereby everbody raise hands as in duaa and says everytime amin to the duaa.

If a Hanafi follows this imaam is his witr also valid? Secondly they start the tarawih rightaway after the fard of isha thus they dont perform first 2 rakaat sunnah. When should I pray this?