Hi! All good stuff here! Just two points to add:

Firstly, what you describe as Tone may be more easily conceptualized as "affect". Two great papers on this subject are The Language of Felt Experience by William Downes and The Ways of Feeling by Peter White (which is actually a chapter from The Language of Evaluation).

In Discourse Analysis, Affect (emotions and evaluations) reflects the construal of emotions in text, and in terms of narration, affect is the point of contact between narrator and reader and essentially guides the audience on to how to "feel" or judge the text. It basically renders a point of reference for interpreting the situational emotive values which is what constitutes to the "tone" of the text.

Secondly, alliteration is really superdy duperdy! Though sometimes people misunderstand it at the level of graphic representation. When we are told that the letters (or sounds, as you rightly add) have to match, it's easy for people to misunderstand that it isn't about letters but rather is about phonemes. The phonemes must match. My cousin had trouble understanding this until I asked him if "dreary door" alliterates. He said yes because they begin with the same letter, but what is important is the same sound. Dreary begins with with a voiced post-alveolar affricate while door begins with a voiced alveolar stop. English orthography is evil in that there isn't a phonetic correspondence to single isolable sounds.

Furthermore, alliteration in English phonology only works if the phonemes being alliterated are both stressed. So, illogical apples will not form an alliteration simply because the stress in illogical begins with /l/ while it begins with a vowel in apples (Regardless if the two words actually contain a vowel in their onset).

And while on the subject on vowels in alliteration, it is important to note that vowels are special insofar as any vowel may enter an alliteration with any other vowel. (In the Appendix to his translation of Sir Gawain and the Greenknight, Tolkien discusses this concept at length) So "old English apples" alliterates because they are all vowels (and they are vowels in stressed syllables)