With roasted beans that old I would leave the grinder alone and toss away the beans.
Even if they were roasted on the day they were given to you, they are stale rubbish now.
As to temperature and grinder setting, I find that humidity plays more part than temp really, but Melbourne doesnt get too much large fluctuations on a daily basis. Anyhow, its often a tweak if I think the shot Im doing is too fast/slow and occasionally a larger tweak. Usually when I dump the shot because it was seriously slower or faster than the last.