Trim very slightly but often. Hair left alone will not grow as fast as hair that it trimmed slightly, as little as you can. You don't want it getting shorter!! My sis had hair down to her bum at school, when she had the time to look after it. Now at uni, it's just shoulder length.
Yes, both of those do. They have all kinds of videos on YouTube that feature different methods to grow hair faster and some of them are really good. Be careful with biotin, however, because it causes some people to break out with cystic acne. You want to protect your hair from the outside using argon oil, eggs, and honey. Taking a multivitamin may help too. Good luck:)