Can we add stats in a gamebook? Like Health, etc. to be displayed at the top of the screen?

yes, but you have to do so through scripting:

'WHATEVER' Page Object -> 'Page' Tab -> Page Type: [script] or [script+text]

and I can't remember if you also got the 'start' Script for the 'game' Game Settings Object or not for Game Book...

but anyways, then use this guide for how to use Attributes and the 'if' Script (scripting is the same for Text Adventure and Game Book, only how you access the scripting differs and also the Game Book is more limited in its functionality/features/Functions):

http://textadventures.co.uk/forum/samples/topic/5559/attributes-and-if-script-guide-by-hk

ask if you need any help with anything