b) What the limits for that particular approach would be for the PAF TU
Tu-154M FM page with minima list for different approaches.
minima-Tu-154M.jpg - Rozmiar oryginalny - Fotosik.pl
Even, if we don't know for sure the particular approach that was used, we can assume that the minima for the aircraft would have been between 100/1200 and 120/1800 m.
The former commander of the 36th regiment was talking a few times about 120/1800, which would mean an 2xNDB approach ("OСП"). I'm not 100% sure what should be the minima for the "OСП+РСП" approach (2xNDB plus an additional limited control from the ground). The same as for 2xNDB?
What we know for sure, in any case the weather was way below the minima.
Arrakis