Answer:
(Fatwa: 1235/1145=L/1429)
(1) According to the Hanfi Fiqh, it is not permissible to perform obligatory salah behind a person performing nafl salah, but other Imams allow it, so he probably prays behind you while acting upon the opinion of those Imams.
(2) You should send his fatwa in his own words, then you will be replied, ins-sha-Allah.
(3) You should perform salah of Asr alone as per the Hanfi Fiqh.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
