Thanks, all of this makes total sense to me.

In the name of “cutting costs” the physical locus of productive labor is moved to global south, with only a kernel of bean-counters left in the home country to “manage” the “investment”. This is the main kind of “work” that occurs in the imperial core. It is why it is called neocolonialism, because formally it is not very different from the “management” by colonial powers over their colonies.

Spot on!

Spitballing here, but I think the primary contradiction in US political economy is finance capital opposed to itself.

Yes, I think you could frame it that way, but only if you bring in the connection to imperialism (as you do, of course, only a few sentences later).