Photoelectric effect minimum frequency

The probability of absorbing two photons is down by a factor of at least 100.

 

So it still can, but it is just unlikely?

What happens when you have many energy levels for the electron to go, so that when the photon hits it it can exist at a higher energy level, and then is hit by another photon before it becomes de-excited?

In The case of no higher energy levels then the electron has no where to go after being hit by first photon and will dissipate the energy before being hit by the second.