That does indeed clear it up a mite for me, Belter. Let's see if I can return the favor.
I've highlighted the overlapping short sides of the cards in the bottom diagram. That's an adjacent move. The B diagram shows a move between two cards where the corners are the only bits touching; no overlap on the short or long sides. That'd be a diagonal move.
As for the spacewalk, I'm going to direct you to the flight manual and see if I can't clear up the murky language. "You can spacewalk between any two modules nearest one another, provided you can draw a straight or diagonal line between them and they're separated by empty space."
"Nearest one another" and the "separated by empty space" are your tricky bits on the red and blue arrow. You can spacewalk along a diagonal or a straight line as far as you want in a single go, so long as you're not intersecting another card. The idea is that it's a single leap through empty space across the vasty nothing. No turns, no crawling along the hull, no lucky spins.