1. The index cards have fourteen lines (light blue lines), the classic sonnet length;
2. “tidy, remarkably clear hand” -- in contrast to the notoriously crabbed handwriting of the six Shakespeare signatures;
3. “not one doubtful reading” -- Shakespearean texts have been a bibliographical nightmare;
4. “a great poet’s work was interrupted by death” -- a point exclusively for Oxfordians, whose seminal work Nabokov must have read. The author, J. T. Looney made that point, contrasting Vere with Shakespeare of Stratford who seemingly retired at the height of his powers. (Please note that I’m not trying to score Oxfordian points here. Nabokov is reproducing Oxfordian arguments under Shade’s umbrella. Whether Nabokov believed them or not is immaterial in this context).
5. Ben Jonson’s ‘Every Man in His Humour contains the following phrases, where he contrasts an “old hackney pace” with a “fine easy amble”. Of trying to walk alongside Shade, Kinbote complains about the difficulty of adapting the “swing of a long-limbed gait” to “the disheveled old poet’s jerky shuffle”. Although time precludes a full exposition, an English version of the name Hamlet was Ambleth, and Jonson’s “fine easy amble” alludes to this. A few lines before Kinbote’s lament, he talks of a “sunset ramble”, and a few lines after, the “solid and ample” text that should have been. Both “ramble” and “ample” allude to the word ‘Hamlet’.
6. Introducing his claim for a 1000 line poem, Kinbote says “Nay” -- an archaic word that plants us firmly in early modern times, not 1959.
7. Ben Jonson wrote that he wished that Shakespeare had blotted (deleted) 1000 lines.
8. Explaining how he came to edit ‘Pale Fire’, Kinbote reproduces a classic Oxfordian argument concerning ‘Shakespeare’s Sonnets’, that Vere’s widow disposed of them for a fee, and they were edited (not benignly) by another. Here, Kinbote takes the role of Mr W.H., in the Oxfordian dispensation one William Hall, a procurer of manuscripts of occasionally doubtful origin, who passed them on to the printer Thomas Thorpe (incidentally, is there not a Mr T. T. in Ada? A conflation of T.T. of the sonnets, and Mr W.H.).
9. In Thorpe’s dedication, he appears to call Mr W.H. the “onelie begetter”. Kinbote uses the phrase “only begetter”. Why Nabokov made this clue so transparent is a mystery to me.
10. There is a second reference to a “tremulous signature”, this time Sybil’s. Yet she is a young woman, or at least not old. 
11. The “old fox” in the publishing business, Frank, is Sir Francis Walsingham, known nowadays as Queen Elizabeth’s spymaster, but also a prolific propagandist for the Tudor cause. According to the 1911 Britannica, he was “in the position of permanent under-secretary of the combined home and foreign departments”. Hence “permanent fixture”. He created the traveling theatrical troupe known as the “Queen’s Men”. 
12. Final point for the time being: Sybil pinged off a wire to Kinbote, asking him to “accept Prof. H. (!) and Prof. C. (!!) as co-editors of her husband’s poems”. According to wikipedia, speaking of the production of Shakespeare’s First Folio, we read that “Heminges and Condell acted as ostensible co-editors”. Ostensible because as actors they would have been unqualified for the task. Kinbote’s skepticism on that very count is emphasized by his ironically promoting them to professorial status: Prof. Heminges (!) and Prof. Condell (!!).

All private editorial communications are read by both co-editors.