If any new Critical Role subclasses appear in the book will they be accessible on D&D Beyond with purchase of this book?

Will WOTC add future Critical Role subclasses as options in the Character Builder?

If any new Critical Role subclasses appear in the book will they be accessible on D&D Beyond with purchase of this book?

Yes, if any new subclasses are added to an official D&D book, they will be accessible on D&D Beyond if you purchase the book here.

Will WOTC add future Critical Role subclasses as options in the Character Builder?

Wizards of the Coast does not own or operate D&D Beyond. D&D Beyond only supports official D&D content so if Wizards of the Coast adds more subclasses, D&D Beyond will endeavour to support them