Those help to shoot better pics and better movies, respectively. It's up to you if you "need" that, or "want" it or "don't care".
I am wondering what additional accessories I need to buy for my new camera I ordered online. How necessary is an external (separately bought) flash and/or microphone for this camera? What would you say are the needed accessories? I was thinking case, extra battery, and memory card. Do I need anything else?