If you don’t reinstall, then yes, activate by phone is legitimate and permanent. During reinstallation, Microsoft products check the key status before you enter it. So even with the same Step 3, it still depends on the key status at the time of entry.
However, you can back up your license for permanent use. See license backup guide

- For Office, Visio, Project: Go to Account, if it shows "Product Activated", it’s permanent.
- For Windows: Open CMD → type slmgr -xpr → it should show: "The machine is permanently activated".

Yes. Activate by phone is a legitimate and permanent license, so you can safely update your system without worrying about key issues.

Step 2 is generated by Microsoft’s wizard, based on your Product Key and hardware info. If either changes, the Step 2 will change. Even with the same key, each PC will have different Step 2 values.

Any country works. It just provides the phone number of Microsoft support in that region.

Yes, while entering the key — to avoid the Multi-Key error caused by entering too many keys. After entering the key, you can reconnect to activate.

The features are the same. VL uses a MAK key that allows bulk activation, usually given to MSDN, TechNet accounts or businesses with volume licensing.

- Activation option doesn’t show due to entering keys too many times without disconnecting from Internet.
- Key mismatch → Solution: retail key must go with retail version, VL with MAK, core with core, etc.
- Not verified, unable to activate → The key may already be used or invalid.