5) I think this is another one they did intelligently and naturally. Shaddiq claims he wanted to protect Miorine. They got along really well as kids, she trusted him, they were open and honest with each other. But Shaddiq accidentally betrayed her. The only way that he could think to protect her was to control her, and that's everything she hates about the way people treat her.
Miorine grew up and learned to start trusting other, and Shaddiq didn't. It's nice to see a series address that people can love and care for each other, but when that trust is broken, it could be a very long time for that forgiveness to happen. Miorine demanded a contract from him to not interfere with her business again, that's how harshly he broke her trust.
Yeah, I'm not so sure about that bit about controlling her. He specifically never wanted to duel for her because he felt that was wrong, but now thinks that the way to protect her was to do so like Suletta did - though she did that unknowingly. She only thought winning the duel would give her a say.

He took her company because he was asked by his father to acquire the Gundam. He didn't want to win it with Anti-GN weapons in a duel and tried to absorb her company instead while letting her maintain control. Miorine didn't see that part at all and just thought he wanted her as a symbol.

I don't think Shaddiq played his cards badly. I think his issue is that he is an heir to a main house, and Miorine despises them all. Suletta was apolitical relative to them.