(2) Most of time I pray the namaz with the half sleeves t-shirt. Is this makrooh?
بسم الله الرحمن الرحيم
(1) In this case the better option is to recite from the Quran kept in the mosque. But in case you are in such a place where there is no Quran available then you can recite from the mobile.
(2) It is not good. One should offer salah in full sleeve kurta.
Allah knows Best!
Darul Uloom Deoband