Is Minecraft free on Windows 10?
No, not legally.
No, only cracked versions.
No, as little as other things that you have to buy.
No.
The Java version was never free.
The promotion that you got the Windows 10 version for free if you owned the Java version before 2018 has been over since April 2020
Unfortunately, no,
you have to buy the Windows 10 Edition (also called "Bedrock Version") from the Microsoft Store. Before you do that, however, you have to find out whether you would rather have the "Java Version". In principle, it is your decision which version suits you better / which versions your friends play.