Just trying to figure things out. In God Jinrai's post it says Prime's at the East outpost, but the characters named off (Sunstreaker, Wreck-Gar, ect.) are all currently at the West Outpost. To confuse matters further, he mentions a large group of 'energy clusters' (decepticons I assume) approaching, which once again suggests the East outpost instead.
You're right- the small group of Bombshell's characters came ahead first. They are at the Western outpost. The rest of the Decepticons will be coming from the East.
The outposts have four walls, a flat top, a floor and communications equipment. They aren't fortified, but they would have steel supports to hold the tf weight. They're meant as lookout points.