Sorry for the delay – I just saw your post.
There isn’t a list of keyboard shortcuts – most of the shortcuts are in the menus. There are a few exceptions, like M to show the original. There isn’t a shortcut for rotating, sorry.
The app does not support multiple access as you asked (two computers using a single drive or a network) except for the Photo library over iCloud.
As far as Windows goes, no. I don’t plan to create a Windows or Android version. The app strongly leverages (and is dependent) on Apple’s technologies, including its RAW engine.