W, v and j were still pretty novel letters at that point. j was typically used as a final form for i/j so you will see things like the roman numeral for 3 represented as iij. V tended to be used for U/V in capitals and u for u/v in lowercase. W was often not a letter that was part of a typefont and writing VV or vv was the only way to represent it in print. The sixteenth century was the point where u and i became the vowel forms and V and j became the consonant forms. Later Latin is inconsistent in its use of u/v and i/j, right down to dictionaries. I remember having difficulty with my pocket Latin dictionary in college because I would often forget that iam was listed as jam in it (and similar instances of an initial consonantal i).
That seems likely. Some early typefaces included wider and narrower versions of some letters to enable justification. Arabic typography does this by allowing, e.g., ﻧـﺪ in place of ﻧﺪ (not a real word, in case you’re puzzling over it, I know more about the letters than the language), where there is an extension to the connecting line between letters.
I think, that Gutenberg’s type had multiple versions of letters for this purpose, but I’m going by vague decades-old memories now.
The printer likely had a limited set of types[1] from which to construct the page. If a page was unusually W-heavy, they probably ran out of W blocks, and substituted VV.
Also, V was considered "just another shape for U" for a long time.
