I've often read that one needs to plant more than one apple tree in one's
garden to maximise fertilisation. I presume the same thing apply to pear
trees, yes?

If so, should each of the two pear trees be of differing stains or the same
strain?

Can pollen from an apple tree pollenate a pear tree and vice versa?

(I already have two apple trees and would like to plant a single par tree,
ideally. I don't know of any other pear trees in the immediate vicinity.

Thanks...
Al