I'm not going to answer all your questions because I'm sure the others have answered them very well. I homeschooled my four kids until 9th grade and they are all off doing cool things now. Their relationship with each other is amazing and one of the big reasons I kept them home.
As far as starting early - I started all my kids very early. My oldest started reading at 2 and was reading Harry Potter when he was 5. I didn't want them to go to college early either but the great thing is that there isn't a finite amount of stuff to learn. We took some very deep dives into lots of subjects. We went heavily into dinosaurs, then ancient Egypt, forensics, etc.
I have no regrets and as far as I know, they don't either. They had fabulous, interesting childhoods and I loved being that involved in their lives.