No. It only reads their files. It never imports, runs or modifies them.

No. The list of 58 API changes ships inside the add-on.

The check is static and only covers the changes in its list. Please contact me through the product page with the add-on name and the error; that is how the list improves.

BREAK: a removed API was found — the add-on will likely fail to load. WARN: a changed or renamed API was found — it may load but some features may break. INFO: only informational findings — good to read but unlikely to break.

Yes. Install it in Blender 5 to scan add-ons that have not been migrated yet. The extension package (4.2+) works in Blender 5.