Derech HaMelech:
1) I’m not sure what you mean by “make it look like it is in its own thing,” but I think you mean “blockquote.” You do this by putting <blockquote> before the quote and </blockquote> after the quote. Also, you can always set off the quote by putting it in italics. You do this by putting <em> before the quote and </em> after the quote.
2) If the person starts with your name (as I did), then you know it is in reply to something you wrote. If there is no name, you just have to figure it out from the context.