Hello,
1) No it is not Windows 10 compatible. But there were reports by users that it still work under Windows 10. But, Stardock does not support it under Windows 10.
2) There is still free 30 days trial version. https://www.stardock.com/products/objectdock/download
3) There is no known timing for future development of ObjectDock at this moment.
4) Not that I know of.
Basj,
Stardock Community Assistant.