*About how long does a normal visit take?
It used to take about 5-6 hours to see everything properly, but given how much stuff has been lost in recent years I would say 3 hours would probably be sufficient now; when
@ThylacineAlive and myself visited last August we spent about that long there and - even though it was his first visit and as such we were covering everything and returning to particular sections - couldn't really have justified spending much longer.
*When is the best time of day to go?
Try to get there for opening time, as this will allow you to view as much of the zoo as possible before the crowds build up; if, as suggested above, you end up spending about 3 or 4 hours at the zoo you would therefore have time to do as Thylo and myself did in August and visit the National Museum of Scotland in the city centre afterwards. Aforementioned museum contains a lot of unusual fossils and taxidermy specimens, including one of only three surviving specimens of the Mauritius Blue Pigeon (
Alectroenas nitidissimus), the only Quagga photographed whilst alive and partial remains of a Bluebuck.
*Considering the fact that the facility is built on a hill, what's the best route to ensure we see most (if not everything) with as little backtracking as possible?
An accurate answer to this would probably be reliant on precisely when you end up seeing the Giant Pandas; however, assuming you see them as early in the day as possible I suggest you roughly view the collection going in a counter-clockwise route as this would take you to the Giant Panda house quite soon after entering the zoo.
*When is the best time of day to see the giant pandas, as they have a timed ticket entry?
As noted, if you aim to view the Giant Pandas as early as possible this will assist with avoiding backtracking around the zoo; moreover it means that if you feel you have seen everything the zoo has to offer you do not have to wait around for hours waiting for your panda slot.
*There are several animals that I will be seeing for either the very first time, haven't seen for an incredibly long time, or are very rare here in the states. What are the chances and/or best times to see the following: Asian lion, Visayan spotted deer, vicuña, Kuhl’s hog deer, drill, gelada, Darwin's rhea, sun bear, margay, Scottish wildcat, Barbary macaque (see next point), pudu, and Chinese goral?
Asian Lion - visible at any time, really. Being big cats and as such lazy, a little luck will be required re: whereabouts in their exhibit they are and thus whether or not they are visible.
Visayan Spotted Deer - visible at any time and pretty showy.
Vicuna - again, visible at any time and pretty showy.
Kuhl's Hog Deer - no chance whatsoever; the last two individuals were PTS sometime in 2016.
Drill - Showy, visible at any time. The only reason you might not see them is if they are in the process of being moved to the current Barbary exhibit and this area is blocked off whilst they settle.
Gelada - showy, visible at any time.
Darwin's Rhea - never had trouble myself but luck might play a part, as they sometimes like to stay hidden.
Sun Bear - there is viewing into their sleeping quarters so even if they are not feeling showy you should still see them in some fashion.
Margay - very little chance whatsoever; shy and nocturnal. Luck will be your biggest hope.
Scottish Wildcat - similar case to the margay, however you have slightly better chance of seeing these as they do like to sleep in the branches of trees and can sometimes be seen doing so.
Barbary Macaque - as long as they have not left, you will see them.
Pudu - used to be showy in their old exhibit, near-impossible in their new exhibit.
Chinese Goral - showy and easy to spot; you'd have to be unlucky in the extreme to miss them.
*I recently read that the Barbary macaques will be leaving soon. Will they still be around by the time of my visit?
Suspect they will be gone, but you never know.
*What is in the huge top two paddocks, as the map only says "Paddock" for each of them?
To the best of my knowledge bugger-all at present, I'm afraid!