>Precedence/associative ... That's it.
Until you get to hooks and forks.
Well, we also didn't mention foreigns (like, functions dealing with OS), punctuation, predefined nouns. Hooks and forks also deserve a description, even though I don't think this is about "precedence/associative" matter - both hooks and forks as a whole are verbs, so verbs rules apply.
>: i. 100
is understood as
>: (i. (100))
- as two monadic (one-argument) functions applied sequentially.
To the left of that application sits the next verb -
FB"0
which applied next, so the whole thing is
FB"0 (>: (i. (100)))
Precedence/associative rules are: all verbs from right to left, all adverbs/conjunctions from left to right, adverbs/conjunctions are higher by precedence than verbs. That's it.