Please give a detailed example of what should happen. Which series of Git command should be invoked?

Are you aware of a well-known port range which could be checked instead?

You can see the annotation in the Branches view, the complete text will be displayed in the tooltip.

This sounds like you are looking for blame information. Because collecting this information is expensive, we won't integrated it in the Log. But you can invoke Blame or Investigate (DeepGit) from the Log (only version 17.1 preview). Investigate will actually honor the selected line from the Changes view.

The submodule entries in the Repositories view primarily represent the "repository root" aspect of the submodule, not the "submodule" aspect (relative to its parent directory). This aspect is represented by the submodule entries in the Files table. Hence, the majority of the submodule-related commands work on these Files table entries. Some of them also work on directories (which must not necessarily be submodule roots).

This should probably be a more general RFE "YouTrack support (similar to JIRA support)"

Please provide more details what this exactly means?

I wasn't aware of this either. I think it will even be better to remove the option.