No. The android licence is only for android. If you want to support the desktop app development you should consider buying a supporters certificate. You can also support in an other way to receive a certificate and unlock darkmode, like contributing in translation, coding, etc. This certificate will work on all desktop OS and multiple installations
No. There are separate licenses for android, iOS and Desktop (windows, Linux, Apple)
The licenses are personal bound. You can use it on as many devices that are yours. For example: if you by the android licence via playstore, you can use it on every device that is connected with your playstore account. Same for iOS. And if you own 2 desktop devices, you can use on both your supporter certificate.
I’m not aware of such a discount.
This is a windows WebDAV problem and can only be fixed by windows. But they didn’t since years now. That why using dokany or WinFSP is recommended.
I don’t think so, as this is not directly related to Cryptomator. A quick google search gave me several guides how to setup a virtual sftp drive like that. When you have done that, you just configure the storage path of your desktop vault with this virtual drive. (Speaking theoretical as I do not use desktop in that way)