Many questions. Thanks for asking.
As I understand it, you can very well charge for your software under foss terms. otherwise it would he free beer, no?
Who would get how much is to be determined. I asked a question and since it doesnt exist, I proposed an answer. So far, I‘m at equal shares. 10 projects means 0.1% revenue for each. If one doesnt take donations, its more for the rest, etc.
If I use a proprietary software I am not liable to their licensing agreements upstream. Pretty easy actually. I dont care what deal micorosoft has with some other dude when I install windows. Thats just absurd. But yes, your vendor would have to pay since they used the code.