As for the road, from 1928 it was expressed the theory of Vucedol-Vatin, straight through the Aquatic (rivers) roads of central balkans to lake Lycnitis (Ohrid) some call it Doric, some call it Mycenean, Giannopoulos describes it at his book through archaiological way,
But could that lead to long Corridor Mycenean palaces culture? or stops to Central Greece to proto-Greeks.
The last I can not decide or support.
Yeah, from what I remember, Giannopoulos mentions (among others) the theory of a potential connection of proto-Greek with Cetina, one of the post-Vucedol cultures, but also brings up that it might be hard to make it account for the known historical spread of Greek considering it seems to affect mostly the Ionian seaboard and the Peloponnese. It's always possible that the exchange was mostly cultural or that it brought some (IE) population elements but non-Greek ones (though the West Balkans of that period are a very plausible source for both Greek and Albanian). It's hard to say when we only have J2a and G so far which seem rather connected with the pre-Greek population.