Probably yeah, but now they've officially released it under the MIT license so stuff like Wine could now potentially borrow some code to improve compatibility with Windows
For the most part probably not, but Microsoft cares a lot about backwards compatibility so I imagine some of this code still lives on in Windows
Though you should take this with a grain of salt, since I'm saying this as someone who 1. never looked at Wine source code 2. used the Windows API only once, for a very small program 3. is still learning programming, so I wouldn't call myself a coder (yet) either