hi, hope i help you haha!!
1- I dont know a way to make a entirely line without having that little space between them, sorry :c
2- the uses of - are simple, i'm going to explain with examples.
First, hyphens - (they are not used when a person says something and they can be used in writing yes, they are used in most part to combine two different words in just one. for example Well and intentionated, you can put these 2 words together, and create one single adjective, well-intentionated or good-looking, but, its not very commonly used, i dont see so many examples about the use of hyphens, and basically, there is not a specifically rule, you have to learn the words that uses hyphen by decorating them.)
Second, the dashes — (as you see, they are longer than the hyphens, and they are the used when someone says something in a narrative, like.
Maria looked up and said:
— What a beautiful sky we have today hum...
so, we used it to show what Maria said.
Third, the " " (its not used for peoples saying. Its used here when we want to mention someone's else phrases, or when the meaning of the phrase is too subjective and figurative. An example,
"If you can dream, you can do"
By Walt Disney.
As you see, its a famous phrase so i have to put " " and tell after who is this from, like i have to give the true owner of the phrase the credits.
Other use is where the word have a different meaning from what it should have, when its very subjective, figurative and etc. Example.
Pluton is a "planet"...
We know pluton is not considered a planet, its a subjective and figurative phrase, its not really correct, so i put " " to sinalize it.