I am trialling Zoho to replace various existing systems, one of which is a customer portal. Our portal allows clients to add and edit bookings, complete forms, manage their subscriptions and edit some CRM info. I am trying to understand how I might best replicate this portal with Zoho products. It appears that I need to combine features of multiple products into one portal. 

Question 1. Which Zoho portal am I best to use as the foundation? CRM, or Bookings, or Billings, or Sites?

Question 2. I found this recent Zoho video on Youtube referencing a Unified customer portal feature but am unable to find any further information on it.

Thanks in advance for any advice.