Yes, you still have to book a slot for the pandas, because there are still a lot of people wanting to see them, particularly now that they are about to enter the breeding season. You can book online at http://www.edinburghzoo.org.uk/visiting/panda.html. You can book your zoo entry tickets online too, at http://www.edinburghzoo.org.uk/visiting/admission/. The extra booking for the Panda slot is free, but essential.
A limited number of panda viewing tickets are also released each morning, for those who have not pre-booked. These are available on a first come first serve basis from the main entrance and are only valid on the day of purchase. Early arrival is recommended.
Brittania is docked at Ocean Terminal, down in Leith.
The Holiday Inn in Corstorphine is right next door to the Zoo and they do a special Panda Package (Google it for more details) but there are so many places to stay in Edinburgh that I am sure you will find somewhere convenient to everywhere you want to go.