Hi Vikram,
Slew will be worst in worst corner.
In worst corner, Id current flowing through the cell will be very less due to operating conditions. When Id (drain current or drive) is less, it takes longer time to discharge/charge Cout (output cap of cell) + Cin (input cap of next cell connecting to). Since Id is less, delay is more. This delay is cumulative as it passes from cell to cell and results in worst slew.
I believe Max cap/Mac load is constant across the corners. I never heard of operating temperature effecting a capacitance or load value. Correct me if iam wrong and justify your answer.
Regards,
Eshwar.