Den, you asked for my sources for
"You could have pointed out that the strike was opposed by PIRA outside prison."
I have books too. Also this
http://cain.ulst.ac.uk/events/hstrike/chronology.htm
It later became clear that the IRA leadership outside the prison was not in favour of a new hunger strike following the outcome of the 1980 strike. The main impetus came from the prisoners themselves.

Re. the SDLP man deciding to withdraw his nomination, my speculation is as valid as yours, and more than plausible.

Re.
"Further more. I voted for Sinn Fein, does that make me something other than "an ordinary decent Nationalist", and if so, what exactly because I've always thought of myself as one."
The majority of Nationalists did refuse to vote Sinn Fein before the cease fire. Were they not ordinary decent folk too.