What are the estimates in total neurons and average connections per neuron for each of the processing areas of the visual cortex?
I found a table listing the relative volumes of 39 different BAs in the supplementary material of:
Hazlett, Erin A. et al. "Cortical Gray and White Matter Volume in Unmedicated Schizotypal and Schizophrenia Patients", which seems to be open-access.

This data is from MRI scans of 148 healthy controls. The mean total brain volume was 1216cm.

Not sure how the density of neurons differs across areas.

Here is a link to the supplementary pdf