Checking through the parts that I'm able to follow in A.S's posting:

1. "On Antiterra the Chillon Castle is known as Château de Byron or 'She Yawns Castle' (3.8). The verb Chekhov used in his letter to Lika, prozeval ("missed, neglected, let slip"), comes zevat' ("to yawn"). In my eyes this is one of VN's less funny puns, of the kind that irritated his friend E.Wilson (cf.VN-EW letters): "Chillon=She yawns"

2.Grigorovich is the author of Luckless Anton (1847) and Gutta-Percha Boy (1883). In the same letter Chekhov says that "we can only beget gutta-percha boys." At one time Aqua believed that a stillborn male infant half a year old, a surprised little fetus, a fish of rubber that she had produced in her bath"

There are various references to gutta-percha in VN's various early works (King,Queen,Knave*; The Gift**) and in connection to his "alphabet in color" ***

3.At the family dinner in "Ardis the Second" Demon praises Lord Byron's Hock: 'Ah!' said Demon, tasting Lord Byron's Hock. 'This redeems Our Lady's Tears.' (1.38)

I suppose that here the reference is to one of those two wines: the "Liebfraumilch" and the Italian "Lacryma Christi." (I didn't check the VN-L but I'm sure it's mentioned there)

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* - "one respectable burgher...was found to have in his apartment an artificial woman. She could walk, wring her hands, and make water...The poor woman turned out to be rather crudely made, and the mysterious substance of which the papers had spoken was, thank God, only gutta-percha."
(the new substance invented by Dreyer is "voskin" used to construct "automannequins")

** - If I had some paints handy I would mix burnt-sienna and sepia for you so as to match the color of a gutta-percha ‘ch’ sound; and you would appreciate my radiant ‘s’ if I could pour into your cupped hands some of those luminous sapphires that I touched as a child, trembling and not understanding when my mother, dressed for a ball, uncontrollably sobbing..."

*** - According to B.Boyd, Gogol was who "first saw yellow and violet" in literature, since he "saw much more than the conventional labels" (Cf. Jean Holabird's "Vladimir Nabokov Alphabet in Color"). Gogol, as also Gumbert Gumbert, could belong to Nabokov's Russian "black group", which includes ahard G, like "vulcanized rubber," and a soft G, placed in the brown group but retaining a rich "rubbery" tone...There is another word, one that starts with a "G" and is directly related to rubber, namely, "gutta-percha", which is differently described...inspite of the persistence of black and rubber in VN's letter "G", "gutta-percha" comes up for its dropping "ch" sound. (Cf. 2007 VN-L archives).

Also in Speak,Memory: "this particular word was first heard by young VN from his drawing master, Mr.Cummings:"I was captivated by his use of the special eraser...he...flicked off, with the back of his fingers, the "gutticles of the percha" (as he said)" ( Speak Memory pg 91).