It's is interesting reading his comments, and I agree that his views are old school. I am not sure that I agree with everything he says.
I doubt that you will be able to get your caique to stay on top of a play top cage. For this reason, I have to move my caique around the house with me, or he will climb or flutter down onto the ground and follow me where ever I go.
He has a large (4 ft. X 30") cage in a bird room. I make sure he has views out the window. It is flat top, but since he is in his cage so much, I do not have him play on top of it. I want all of his out-of-cage time to be away from the cage he is confined in for hours every day (and so does he). So the bird room is only for in cage time. (Now if I had a set up like Saroj that would be different!).
He has an avian adventures chiquita play top cage to eat on top of in the dining area (he will only sit on top of this cage long enough to take a couple bites and then he climbs to the floor). He gets the whole kitchen island to himself at dinner. (We eat together there). He is all over it hopping, getting into whatever I have out, trying to prompt me to chase him with my hand. He sometimes flutters to the floor (but is mostly focused on eating his food, eating my food, and wrestling). He gets the bathroom counter to himself (and has managed to shove one sink drain in so far that it needs a plumber...for the second time). He has a night cage near the bedroom for sleeping. He has a stroller. He also spends a lot of time running around the floor of the house. I try to keep an eye on him when down, and he tries to keep me in sight. But every now and then I will find him in the shower, with the drain disassembled...So I guess what I am saying, is that I would recommend one large cage (the largest you can find) and lots of spots around the house for your bird to hang out with you. He will demand no less.
If your new bird is anything like mine, you will find that it needs constant stimulation and attention. It will want to be with you ALWAYS. It will get bored very easily. It can become aggressive and vocal (this happened at around 4 yrs of age) if it thinks you are not paying attn. to it, or following the established routine that is all about the bird. It will want to be the center of your life and it will not understand why it cannot be with you ALWAYS. I do not think this is the bird's fault in anyway. It is not a human, or a domesticated dog, but a flock oriented animal.
For these reasons, I would like to have had a second caique. I imagine my boy playing with her on the living room floor while I have my morning coffee (in peace). Or eating together and grooming each other while out; Chasing each other, surfing and romping around the house. I completely agree with Saroj as to the timing of a second caique.
I agree with the vet re: that bilevel cage. It is horrid. I hope he no longer keeps his wife's african grey in that cage, realizing its shortcomings.
I do not know that I agree with him completely as to diet. I think pellets are fine, as are nutriberries, but I think variety, including fruit and vegetables are important. If you look at the back of a caique's tongue, it is feathered. I cant help but wonder if they eat some nectar in the wild, and if so, fruits would seem to be an important part of the diet.
Whatever you do, dont forget that these are wild animals. You cannot mold them into little children (says the one with the stroller, lol). They want what they want and that is how it is. They weren't meant to live in cages in houses with walls and ceilings. But here they are now, and all you can do is try to keep them as well fed and stimulated as possible....for 30+ years.
One thing he has that can not be replaced is experience. Hands on, down in the trench medicine. I admire him a great deal. 
.
