Or is it implied signals always have to go back and forth between the thalamus and the cortex? Or is it possible they do both at the same time? Or maybe for areas next to each others they can go directly but for total different regions of the cortex they have to pass through the thalamus? Note: I...

Both are correct, technically, neurons a lined and positioned through synaptic connections and so logically each layer should comprise both the soma of neurons as well as the neurites for synaptic connections that can or may extend outside its layer and protrude its network outside. I highly reco...