Compare effective durations of callable, putable, and straight bonds.

In the Compare effective durations of callable, putable, and straight bond section there are several points that I do not get.

what does this mean:

Effective duration (zero-coupon) ≈ maturity of the bond.

does this mean that the effective duration almost equates the value of the bond at maturity, if so, why is that?

Why is that? Effective duration of fixed-rate bond < maturity of the bond.

what does this mean: Effective duration of floater ≈ time (years) to next reset.