re: Globular Clusters
An advanced ETI would not have to originate from a globular cluster, just reach it and utilize its resources. Having all those stars and any planets circling them in such close proximity would be very tempting to a Kardashev Type 3 culture.
The article I linked to in my other posts lists M22 as a favorable cluster for such a purpose.
Of course, there is the chance that some globular clusters were not formed naturally.