I’m running a series of exterior plugs on a renovation project - I live in BC, Canada for reference.

Two questions,

1. All boxes will be inside the wall cavity (everything is open and exposed inside) - can I use a metal box? Purpose of this is to extend the box out further so that when I trim it out on the exterior (and flash, and rain screen, and Tyvek) that I don’t need really long screws to hold the outlet in place in the box.

2. Do all plugs need to be GFCI rated, or, when I’m running a series of (3) plugs, does just the first one require it (so long as the other two are powered up from the bottom terminals on the plug and have weathertight covers) or do they all need to be?

TIA