Please do not tell me about the history of Kanji! I know where they come from and why they exist! I know that they have two kinds of readings, the Chinese Onyomi and the Japanese Kunyomi! I know quite a bit about Japanese, but I can't find anything going into extreme detail about what Kanji is.
Kanji seem to have their own meanings, but from what I've seen they represent syllables in a word, sometimes not even a whole word. Forgive me if I am making a mistake, but I believe an example of this would be 食, meaning "to eat". The Kunyomi of 食 is "た", but it isn't a word on its own and needs to have "べる" added to it to make it "たべる". So are Kanji symbols that are not words but still have meanings, and are used as letters of some kind where even if it is possible to phonetically spell a word using other Kanji you have to use the ones with the correct meanings?
I also have a problem with Onyomi and Kunyomi.
Are Onyomi actually used as words or only as parts of words? What I mean by this is, is it possible to say a sentence with only Kunyomi words, and then say the exact same thing with only Onyomi words? It might seem like a stupid thing to ask regardless of what the answer is, but I'm having trouble understanding because I'm seeing Onyomi and Kunyomi as two languages to an extant.
Is it sort of like how we have Latin, Greek, French, and German roots, suffixes, and prefixes? "In" is from Latin(I'm 99% sure...) but doesn't have any meaning on its own but becomes part of words like incredible, or infamous, or how words may be changed or have things added to change their meanings, for example did, does, do all have the same root but are changes, or will, would, were, and won't where they are all changed but are all a different form of the same word and where won't is even changed to where it has a part that otherwise wouldn't be a word "wo".
I hope I'm not the only one who has any idea what I mean, but thank you for reading. If you don't know exactly what I am asking I would be more than elated if you just told me EVERYTHING about how Kanji work from the smallest detail.
Thank you.