Do you ever use side light, reflected light etc?
Side light is better than front light! And reflected (or diffused) light is always better than direct, harsh light! So you do the best you can with what you’ve got. 🙂
And of course, this is all in context of getting flattering pictures. If you’re taking a picture of a villain, then, well, direct harsh light from below might actually be what you want. 🙂
How do you deal with the squinting eyes (that sometimes come from facing into the sun!)
The harder someone laughs, the more their eyes will naturally squint. So, get everyone laughing really hard. 🙂
As for your other questions about the direction of light, are you familiar with the different emotions associated with the different angles of light? Here’s an article that actually uses some clean examples that I think explains the basics well enough: https://photovideocreative.com/en/light-direction-emotions-choice-light-position-photos/ I generally stick with backlighting or “loop lighting”, where the light source is slightly higher than eye level and about 45 degrees to the right or left of the camera.