Well the methods are quite short so it could probobly all be rewritten to be pasted in an event script command, but using methods like that is handy.
I might have over complicated things a bit really. If you wanted to do it in the simplest way possible all you would need to do is this to get the four nearby region_ids in an array is:
x = $game_player.x
y = $game_player.y
[region_id(x + 1, y), region_id(x - 1, y), region_id(x, y + 1), region_id(x, y - 1)]
Or you could put them all in different variables or something. It's just adding and subtracting 1 form the x and y really.
Anyway, as for your other question:
Assuming 'actor' is the actor you want to check, you can use this in an if statement or a conditional branch script call I think:
actor.weapons && (actor.weapons == actor.weapons)
Not sure what actor you intend on checking or where you want to use this so I can't exactly give you anything more exact.