Even if they don’t, the n95 will filter better than whatever lower-grade mask they were otherwise wearing.

Will it? If your beard prevents a seal you're just going to be sucking in air from through the sides like you would with a standard mask, no?

some will go through the mask (and be filtered).

Kinda like adding a 100kohm resistor in parallel with a 10k ohm. Most current will go through the 10k, but there will still be some going through the 100k ohm.

yes, but if it's not forming a tight seal it might not be filtering enough to matter