I'm making a website, need some help

I am making a website sorta like na.op.gg where you can look up people's stats n stuff. I am in a 2 web coding class and I have an API key. My course will go over PhP, JS, HTML, MySQL, and a few others. I have a few questions about designing the website.

• What artwork is legal to have as my background (can I take fanart/official art?)
• What type of code does it use (for the API)
• A good free and safe web designer? (like Dreamweaver except free)
• A good way to get traffic?
• Where can I find example code for Riot API projects?