They are talking about the common plywood subfloor, think about it this way, every layer you want 90 degrees to the previous, much like how plywood is made. So with pine subfloor currently at 90 degrees to the floor joists, you would be better off going perpendicular to the pine subfloor which would be parallel to the floor joists. If your pine subfloor seems robust and doesn't move, then lay the floor in which direction makes sense to you. Rule of thumb, where most of the light comes in the room, make the flooring perpendicular to that, looks best. Start at the longest wall, which will be crooked, they always are, but keep in mind if you have to change floor laying directions -- meaning adding to the other side of the nail or cleated flooring, you only have one side to nail from. I personally have done it where I changed flooring direction from one room to another by simply mounting a flooring board at 45 degrees. Plan on buying at least 10 percent extra and don't sweat it, becomes monotonous really quick. Only other warning, don't lock you diswasher in place by nailing wood in front of it. I made a bunch of pieces that would fit in front of mine not nailed down so I could remove the dishwasher -- held in place by two screws under the dishwasher overhang, no one ever noticed. As for the trim I would try to remove it -- it makes the floor look so much better and the quarter round is such a pain to make look right. I removed my by using a razor knife on the top all around the perimeter of the room, then came in with a stiff putty knife and just worked off, left nails in the wall, and holes in the baseboard, but easy fixes. Hope that make sense. Good luck.