and they are steadily working away on it. the station building exterior is finished (not sure about the interior), they built a subway extension to connect with the nangang HSR station last fall, and put the regular rail station underground shortly after. it'll be helpful for feeding east coast ridership into the HSR system, as all trains to keelung and the east coast come through nangang. they just built a major bus terminal/subway station on the east side of town for similar reasons, taipei main station is horribly crowded, since everything goes through there.

i don't know much about the state of the three middle stations, unfortunately.

it is my understanding that the HSR will go to kaohsiung train station. i certainly hope that's still the case, it would be loads more convenient than the station in zuoying (which, to be fair, is still fairly well linked to kaohsiung's subway system, which opened just a couple of years ago).