The DoD helps the developers know how much work needs to be done, and therefore they can decide what should be part of the sprint. It also creates a shared understanding of what done means. This is likely to include documentation, but that depends on the decisions of the organization and team. Scrum does not dictate this.

In the scrum guide it says: "The purpose of the Sprint Retrospective is to plan ways to increase quality and effectiveness."

Review the scrum guide section sprint planning if this is still an uncertainty for you.

The scrum guide says: "The Daily Scrum is a 15-minute event for the Developers of the Scrum Team. "

It's definitely a good practice. And not because you can see the code coverage (which also isn't an excellent metric of quality and progress), but because you can detect problems before moving on.