Only when you press a fix. Scanning is read-only. Every fix is classified Safe, Confirm or Manual, Fix All Issues applies the safe ones and asks once before the confirmable ones, and the whole operation is a single Blender undo step.

That the add-on knows what is wrong but not what you intended. A flipped normal can be recalculated; a naming convention that two objects disagree about cannot be guessed. Manual findings are listed with the reason and left for you.

Yes. Copy any built-in preset into an editable profile and change severities per rule, or store a project snapshot with the .blend so the file carries the standard it was made to. Profiles are portable; project snapshots travel with the scene.

Three usual reasons: the scan scope excluded it (Selected Meshes only checks the objects you chose), a collection exclusion covers it, or the rule is disabled in the active profile. Findings that could not be evaluated appear under Diagnostics rather than being silently dropped.

No. There are no network requests, no telemetry and no account. It works with the machine offline.

No. The three are independent and can all be enabled together.

It reports progress as it goes and can be cancelled at any point; cancelling keeps the results it already had rather than discarding them. Narrowing the scope to Selected Meshes or Active Collection is the usual fix for an iteration loop.

Blender 3.3 through 5.2 - the extension build covers 4.2 and newer, the classic add-on build covers 3.3 - 4.1. The release matrix passed on 4.3.2 and 4.5.2 LTS. Marketplace v1 is Windows x64.