The scout’s “Proximity Mine” skill disappears after he either left the game or after several missions, I haven’t found out exactly yet! What to do with it?
You can pump the scout again, through a token, but that will not be enough tokens)!
From what ive seen, after you beat the campaign you can reset skills as much as you want (at least in jacked mode) furthermore with how slowly gears level its better to replace old gears than level them up.