1. Genma has done a far better job of preparing Ranma for carrying on the school than Soun has done with Akane.
To be fair he doesn't want or have any intention of Akane carrying on the school, he wants Ranma to.
I agree with the rest though. Well maybe not point 8 since Soun may very well have a job just not shown on screen (he does use going on a business trip as an excuse once and if he didn't have a job of some sort that wouldn't work as an excuse). Genma maybe pretty bad but he is more useful than Soun, who is basically useless. Also a lot of the bad stuff Genma has done is in trying to help Ranma. He used insane and brutal training methods to make Ranma stronger, not out of spite or malice.