New to r/drones and I've got some questions

Hi guys, really glad I found this Reddit page, I've had a DJI Phantom 4 for a couple years now, but never really got to use it too much, but I'd really like to use it more. I used to live in the suburbs and didn't really find a lot of opportunities to get some cool shots, but now I live in a city and was doing some video editing at work of some drone shots a guy took years ago and it looked really nice, so I want to start getting back into it. I have a couple of questions, I hope they don't make me seem too dumb, and I appreciate1) Is it legal to fly them in the city? Do I need a license/register my drone?3) Any rules of thumbs I should know about before flying it in the city (ie don't fly over streets or go too low)?2) Anyone with some experience flying in cities has any good ideas for cool shots I might be able to get? via /r/drones http://bit.ly/2RngSPS