Answer
(Fatwa: 1002/807/B=1431)
(1) According to Sharia it is alright doing umrah more than once in a day.
(2 & 3) It is right for both alive and dead ones.
(4) It is wajib to wear ihram before each umrah and shave the hair of head passing razor after umrah.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband