The Stand-Alone Addon Manager version is entirely irrelevant, since you said you installed the latest one, and that will update whatever modules and code needed to be updated to the very latest version, regardless which version you had before.
Also, if you are going to download the full installer anyway, which installer you used originally is not relevant anymore.
And, NORMALLY, if you download just the full GSX installer, it always contains everything, so you don't need anything else. However, since we are still in Beta with the latest Couat 3, we haven't updated the full GSX installer in a while, but we HAVE added a couple of liveries in the meantime in the separate vehicle installers.
So, while we are in Beta, if you download the full GSX installer and the latest vehicles update (Nov. 2014) and THEN the Couatl 3 Public Beta (in this order), you have everything updated.
When we'll be out of Beta, the new full GSX installer will contain again everything in a single download, as usual.
