Answer
(Fatwa: 1260/L=327tl=1431)
(1) This practice of yours is all right. Salah is not valid behind such an imam who does masah on such a cotton socks, which do not fulfil the conditions of masah. However, you should offer salah in any other mosque with jama’ah and if it is not possible, then you should offer salah with jama’ah together with some people separately so that you are not deprived of the virtues of jama’ah.
(2) It is not lawful to do masah on such types of socks according to any Imam.
فإن كان رقيقين يشفان الماء لا يجوز المسح عليهما بالإجماع (بدائع الصنائع 1/10)
(3) If you offer salah individually then you will not get the reward of jama’ah. However you are helpless hence you will not be accountable for missing jama’ah. If you along with some people arrange jama’ah separately, you shall get the reward of jama’ah.
(4) Same as the answer no. 1.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband