Both you and Fonstad state this but I cannot find the reference in UT. Moreover, there must have been a sort of permanent garrison at Lond Daer if for nothing else to oversee the shipments of timber. Again, since these men had to eat, there most likely was some sort of agricultural system in use, implying a (semi-) permanent settlement. It is true that in UT (p.206) it is stated that the works that Tar Aldarion (SA 700-1098) began at Vinyalondë "were never completed" but, as Christopher Tolkien points out (UT, p.265) "This probably means that no more than that they were never completed by him [i.e. Aldarion ]".

: Vinyalonde was usable, and perhaps inhabited, in SA 1700, when the Numenorean admiral Ciryatur sent part of his fleet to the haven to land a force behind Sauron's lines

As said above, I believe that it must have been inhabited far earlier.

: In Unfinished Tales there is a note where Tolkien writes that in the early days travel between Gondor and Arnor was fastest by ship travelling from Anduin to Tharbad. This seems to imply that Lond Daer Ened was no longer inhabited.

Actually what he says (p.264) is "The ancient sea-port and its great quays were ruinous" which doesn't necessarily mean they were in ruins. Logistically speaking, someone must have lived there, if only fishermen and merchants.

: Sometime before Elrond retreated to Rivendell, the Numenoreans made a port at Tharbad

According to Foster (p. 426), Rivendell was founded in 1697 by Elrond who "was fleeing from the destruction of Eregion". In UT (205-206) , however, it is said that "It seems that when Aldarion became King of Númeor in the year 883 [SA] he determined to revisit Middle-earth at once, and departed for Mithlond either in the same year or the next [and he ] went up the Gwathló as far as Tharbad, and there met Galadriel". Ergo, Tharbad must have been founded in the years immediately following the foundation of Lond Daer (some time between 750 and 875 SA).

: One attempt was made to recolonize Cardolan (sometime in the 1800s), but by then the barrow-wights had settled in Tyrn Gorthad and the colonists were too terrified to remain nearby, so the attempt failed

If Cardolan corresponds roughly to Minhiriath, I don't understand how Tyrn Gorthad could have affected any settlement south-west of the North-South Road.