A:AnswerDigital is a download that installs and runs on your Wii U, while the regular version is a disc that you have to have in the Wii U disc drive in order to play.
A:AnswerThe eShop is not closed on the Wii-U yet, so yes you would be able to play it. I just bought this tonight and did so.
As of 1-31-21 there has been no word of any date as to when it would be.