I am looking for a way to remotely teach a class
For the video conferencing software, I recommend Discord.  It was started in the gaming community. When we all went online in March, several of the students in one of my classes suggested it, and I went with it.
It's very good for low-bandwidth voice channels, and also allows screen-sharing.  The only downside is that it only allows 25 people to see the screen share at once.
To get around that, a colleague of mine streams his video feed to Twitch (another gaming site).
As far as drawing, I use Microsoft's OneNote software. Its drawing allows my to use my Wacom tablet to write on top of PDFs that I upload into it.
Below is a still from one of my video lectures, showing my (awful) handwriting on top of a PDF in OneNote. This was streamed to YouTube for recording purposes, but most of the students were watching live.