[fn]+[up arrow] = pgup, [fn]+[down arrow] = pgdown, [fn]+[left arrow] = home, [fn]+[right arrow] = end

They're called the navigation keys. Fn + Up/Down (arrow keys) is PgUp/PgDn, and Fn + Left/Right is Home/End. But of course, those keys are on completely opposite sides of the keyboard, so Space is more convenient.

>the home row (don't know if that's how that row of buttons is called)

the "home row" is where your fingers start out if you know how to type by touch, and it come from the days of typewriters instead of keyboards.

on a QWERTY keyboard, the home row is ASDFGHJKL; with your fingers resting on ASDF and JKL;

when they teach you to touch type, they say "put your fingers on the home row" and "home is where your fingers always return to."

"Home row" usually refers to the row where you initially put your fingers when touch typing, to not have to move them much while typing.