Operability between Scrivener 3 on Windows, MacOS and iOS.

Scrivener Scrivener for Windows
1

Will version 3 be able to be manipulated on both my Windows laptop and my iPad?
Will a version 3 come to iOS as well as Windows and MacOS?

2

Yes.

iOS already supports both the v2 and v3 file structures. For instance, currently one can sync a Win Beta project between Windows and iOS.