To answer some of these questions:
- Year 2 can be installed without Year 1 being installed (but due to the nature of cumulative updates, we require you purchase both Year 2 & Year 1 for any device receiving Year 2 updates)
- Year 2 can be installed early - and Year 1 updates will install
- Year 1 ESU includes those updates released on January 12, 2021. Likewise Year 2 updates will include the updates released on Patch Tuesday 2022
- There is no test key for Year 2
- Visual Studio subscribers do not get an ESU key for testing. However, you can use your ESU key for testing in a test environment. If you run out of activations because of the test devices, you can request more activations at no charge
Hope this helps. Sorry for being so late, its not my blog so I hadn't been checking for comments.
Microsoft