Who is paying their respects to Juliet at the start of act 5?
Act 5 starts with Romeo in Mantua, talking about his dreams. Nobody pays respects to Juliet until Paris does, later on in the act.
Which lines from act I of Shakespeare's Romeo and Juliet suggest that Lord Capulet respects free will?
It's not like Capulet (he's never called "Lord" in the text) has a lot of lines in the act, and most of them are in scene II. If you mean by "respects free will" that he intends to respect Juliet's opinions on just who she is going to marry, your lines are probably "My will to her consent is but a part; an she agree, within her scope of choice lies my consent and fair…
There are four different fights in Romeo and Juliet: one in Act One, two in Act Three, and one in Act Five. Gregory and Samson start the one in Act One. Mercutio starts the first one in Act Three and Romeo starts the second, although he is reponding to a challenge which was earlier given to him, so in a sense Tybalt started it. The fight in Act Five is started by Paris.