Answer
(Fatwa: 479/345=L/1430)
It is unlawful to deliver khubah in non-Arabic language, trimming beard beyond Shariah limit and wearing jubbah below ankles. Therefore, performing salah behind such imam is makrooh. It is better to go to any other mosque where the imam is having correct beliefs, following sunnah and is aware of salah rulings. If someone has to pray behind the abovementioned imam, the salah will be valid provided he (imam) fulfils all the conditions of Taharah etc which are necessary according to Hanafi Fiqh.
(2) A Hanafi can pray behind a Shafe?i imam provided the imam does not do any thing which nullifies salah according to Hanafi Fiqh.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband