And except for the absence of the Illusive Man they were EXACTLY that in Mass Effect 1. That is, to the extent that you could tell any two missions apart, but that's Mass Effect for you.
No it's not. All we saw of Cerberus is a handful of VERY SMALL outposts scattered over a few isolated planets. We don't even know if Cerberus built them for purpose or just co-opted some abandoned survey stations.
In ME2 & 3 we see them with at least large space stations, one of which is equipped with drydock facilities, several VERY LARGE and purpose built facilities with their logo slapped on just about every wall and door. In terms of assets and manpower it's several orders of magnitude greater.