I have just started studying Japanese and using WaniKani. Therefore I can’t fully grasp the examples in “Word Use” and “Context” sessions of each lesson. When I reach the end of level 60, will I have learned all the vocabulary words necessary to go back to each example and understand it? (Not considering grammar.)
Not necessarily no.
Wanikani doesn’t teach katakana only words (for example words borrowed from English), and hiragana only words (like onomatopoeia) but there are a large number of them, so it would be quite difficult to make interesting and natural sentences without them.
Also the vocab in WK is selected to reinforce the kanji, so sometimes some fairly common vocab are not in WK because there are already plenty of (also common) vocabs covering that kanji.
About the example sentences, usually the first two tends to be a bit easier, but the third one is usually more advanced and anything can go, even rare words.
Not really, a simple example would be all the katakana and hiragana-only words that you encounter in it, and I’m fairly certain there are kanji words they just won’t teach in there. However if you start reading around level 20-30 and continue that, you will be able to understand them mostly by the time you’re level 60, if not earlier
The bigger thing is grammar knowledge in understanding the sentences. You can just look up individual words on jisho or whatever.