Cyclone output impedance

I have 2 questions regarding the Cyclone(EP1C20) device -

How do I calculate the output impedance of IOs(Pin C5 on the 400 pin BGA) on Cyclone or any IO for that matter.

We are using 3.3V CMOS for IO.

Also, in Pg 101 of the Cyclone literature, the set up time is 4.0ns and hold time is 0ns (for speed grade 8).

But how can hold time be 0?