Here is how we interpret the distance thing:
Close = engaged combat. fists, knife, short sword, mace… You can reach out and touch. Characters can whisper to each other.
Near = two handed weapon distance. Spear, halberd, 10’ pole, long sword, lance, whip… You can reach them with a physical extension. Characters can speak at normal volumes.
Far = anything further than near. Ranged weapons, bows cross bows, sling, etc. Characters need to raise their voice or shout.
For vehicles or ships: Close, you can see the faces in detail on the other ship. Near, you can see the silhouettes but not facial expressions. Far, everything else.
I thought the rule book was pretty clear on how they interact with actions, @Skippy already posted those.
JMHO