Learn English – Principles in the use of letters ‘b’, ‘u’ and ‘v’ in Early Modern English typography

I think would and flood are or were rhyming pairs in some dialects of English. This is not surprising, as /ʊ/ (as in would) and /ʌ/ (as in flood) are similar vowel sounds. I think in some dialects of modern British English, the two vowels are merged. The general term for words that almost rhyme is called slant rhyme. Words that are spelled like they might rhyme but are not are called eye rhymes.

As for the second passage, I think it is just a rhyming pattern of AABC DDBC.

It appears that the style you are referring to is actually from the 16th century:

• Garamond is the name given to a group of old-style serif typefaces named after the punch-cutter Claude Garamont, (also spelled as Garamond, Latinised as garamondus) (c. 1480–1561). Garamond’s letterforms convey a sense of fluidity and consistency. Some unique characteristics in his letters are the small bowl of the a and the small eye of the e. Long extenders and top serifs have a downward slope. –

• The first Roman type designed by Claude Garamond was used in an edition of the Erasmus book Paraphrasis in Elegantiarum Libros Laurentii Vallae published in 1530. The Roman design was based on an Aldus Manutius type, De Aetna, cut in 1455 by Francesco Griffo.

• After Claude Garamond died in 1561, most of his punches and matrices were acquired by Christophe Plantin from Antwerp, the Le Bé type foundry and the Frankfurt foundry Egenolff-Berner.

• A direct relationship between Garamond’s letterforms and contemporary type can be found in the Roman versions of the typefaces Adobe Garamond, Granjon, Sabon, and Stempel Garamond.

Garamont type-style.

The use of italics for some nouns may derive from the style in vogue during Renaissence times. Italics was popular in handwriting ad was probably used in printing because of its elegance and clear reference to an 'erudite' style.

• The humanist spirit driving the Renaissance produced its own unique style of formal writing, known as "cursiva humanistica". This slanted and rapidly written letter evolved from humanistic minuscule and the remaining Gothic current cursive hands in Italy, served as the model for cursive or italic typefaces. As books printed with early roman types forced humanistic minuscule out of use, cursiva humanistica gained favor as a manuscript hand for the purpose of writing.The popularity of cursive writing itself may have created some demand for a type of this style. The more decisive catalyst was probably the printing of pocket editions of Latin classics by Aldus Manutius.