More than likely that figure (27 miles) was for the axis of the stream. That's the center, not the extreme Fla edge. The stream can do very strange things after rounding Cape Canaveral; eddies and swirls, and these can interfere with the counter current normally found near shore. The stream is kinda like a magical mystery tour; I don't know if anybody understands all it's peculiarities.
I don't think so - right now, NOAA is reporting the west wall of the Stream to be 43 miles E of Ponce:
The approximate location of the west wall of the Gulf Stream based on data from the real time ocean forecast system on Friday September 27th. 43 nautical miles east of Ponce Inlet. 34 nautical miles east of Port Canaveral. 29 nautical miles east of Sebastian Inlet. 21 nautical miles east of Fort Pierce inlet. 13 nautical miles east of Saint Lucie inlet.
I have never found the Stream to be as remotely close to shore in that area as you've described... There can be plenty of weirdness/confused seas passing close by Canaveral, but that's often as much due to the shallowness of the water, as anything else... Running coastwise or as close to the beach as Harborless was, the first encounter with the effects of the Stream I generally find is just south of St Lucie Inlet, the waters off Hobe Sound and N of Jupiter Inlet are always pretty stirred up by back eddies off the Stream...
Once past Palm Beach, the axis of the Stream usually runs just about due N at least to around 30 N. Last time I rode the Stream north was back in June, Chris Parker suggested the axis was running at 79 50 W up to around 30 N, and he was right on the money, we nailed it all the way up to Hatteras, making it from Ft Pierce to Annapolis on an H-R 43 in 4 days, 2 hours...