Short version. I don't really care, keep it off the floor.
Long version. The choice you make in what you look like defines who you are and makes you stand out. If you choose a hairstyle you like, you'll find guys who like that hairstyle and that's f***ing magical.
depends on the person but it risks the "too long" look more easily when it is all one length and thin at the ends. if you keep it layered/angled and trim it regularly so your ends don't get stringy, it can look nice. although once it goes past your waist it usually looks too long, unless it is that style where there are a lot of layers and the front is shorter than the back.