Zoom has an excellent tutorial series for setting up and using Zoom. It allows you to learn step by step, form beginning to advanced.
There is a link on the footer ofd each page.
I recommend using a photo for your profile picture. The picture you choose should be able to work with a wide range of audiences.
Here is a pretty good tutorial for how to fix the issue of your profile pic not showing up.
When you present your projects it is good communication practice to use your video camera so that your audience can connect with you.
There are some cases where your internet may not be able to stream your video and then it is ok after mentioning that to your group that you will be turning your camera off.
It is appropriate to turn your camera off when you are working on your project, not presenting, not asking questions, and not in a discussion.