I’m not quite sure I’m understanding what you’re asking about quoting posts.
If you mean “how do you quote a post” in general, you can highlight however much of a post you want to quote and a little box should pop up above the highlighted text with two options - ‘quote’ and ‘share’. When you click ‘quote’, the reply box will appear with the quoted text, which will also display the user’s name and pfp.
Is this what you’re looking for when quoting a post:
[name_u]Or[/name_u] do you mean this? For the one below I just deleted the text between the " ".
And to answer this question, you can add a line by entering 3 underscores (_ _ _) or 3 hyphens (- - -) on their own line of text. The spaces between the underscores/hyphens are optional.