Tween the drawing process and change multiple keyframes at once [Need help]

Hello,

I try to create explanation videos from scratch. Thus, I mainly draw lines and create keyframes that it looks like I would be in the process of drawing. For straight lines and different shades, I use the line tool and form tween. I have multiple questions to speed up the process.

1) Is there a way to film the drawing process and convert it into a tween? It appears very tideous to draw letters and shapes over multiple keyframes and add/delete keyframes to meet the flow of the video without dropping frames per second.

2) How can I make a change in multiple keyframes at once? I sometimes run into the problem that I drew a line accidently and I notice it about 100 of keyframes later. If there is something missing, you can cover it with another layer but deleting appears to be an issue to be dealt with in every keyframe seperate.

3) Is there a way to determine the path of transformation of form tween? I tried to draw mathematical functions with form tween. Form tween does allow me to change the "drawing time" afterwards. But it curve does not propagate along the function. It rather looks for a point-to-point way which does not look organic. This question would be solved if there is a solution for 1).

Thanks for the help in advance.