Hi, congratulations on your new Galaxy and welcome to the forum. Nice to have you with us as a member of Android Tablets. I'm moving your question to the Samsung Galaxy Tab 8.9 section to see if anyone can answer it for you.
Yes, Whatsapp can works perfectly on 8.9 and 10.1 as long it has 3G connections. I've installed on my wife's 8.9 and during the installation, I've screen captured each step and composed with final cut pro to make a tutorial. Please check the link below, I hope it'll help you.