PH4 has an even better camera. The camera on Mavic pro isn't that great in the end but if you're going for the portability and usefulness over the quality I recommend the Mavic Pro. This video shows the quality differences of the 2 cameras. You can notice how wide the PH4 lens is compared to the Mavics

PH4 is also more powerful. This can come in handy when flying in high wind speeds. But again the choice is up to you; do you want portable drone or a drone with better quality?

And yes checking your local laws is important. It has been in the news over and over again how some people fly over the limit and almost cause accidents. You don't want this to happen. Mostly you are just fine by using common sense such as don't fly over crowded areas, don't stalk other people, do NOT fly near airports and make sure that you know your surroundings to avoid accidents. These drones are toys but very powerful toys.