Discord

Not at all. Discord was originally a gaming platform, but now serves study groups, hobby clubs, professional teams and fan communities and even some classrooms.

Yes. You can also make peer-to-peer one-on-one voice and video calls (the Zoom or Skype way) with no server involvement.

Features that help ensure safety with an arsenal of blocking, reporting and friend request controls. However, due to the fact that users can join public servers as well direct messaging strangers parental supervision for younger teens is suggested. Minimum age: 13 (depends on Country).

Text channel is for typed messages, images, links and files. Voice channel is just for live voice chat (you can also share the screen or go on video). Text chat exists with voice channels as well but it's to the side of it.

Yes. Discord offers iOS and Android apps that enable most desktop features as well, such as background voice calls and push-to-talk.