parametric

[drifting summit]

watch lord cook

watch LordDarpinger cook and spit facts

[twilit knoll]

Both x(t) and y(t) are function with period 2π. So, that's how much time you need.
As for the speed, we have:
|v(t)| = √((dx/dt)^2 + (dy/dt)^2)
This is the instantaneous speed at time t, but you'll see that in this case it is constant, so it will be equal to the average speed.