XPM algorithm explaned

I’ve posted a thread here:
I’m curios if anybody can explain me how XPM algorithm works specially part that satisfy requirement of nonreusability.
Other questions are:
Is a hash rate of 1GHash correct (https://coinplorer.com/Charts/Difficulty/XPM)? Does it mean that there is 1E9 candidates tested every sec?

Than you in advance for answering.