Im not sure about most your questions but I'd like to comment on the cagesize, I saw your in norway so not to far off from here

anyways here we got something called L80 wich declares what the minimum sizes of cages we may use to hosue different species of animals are (including birds) and basically the smallest cage your ever allowed to use here is 45cm X 70cm and 60cm high and the largest birds your allowed to keep in these cages are lovies at their 15cm (beak to end of tail) and if im not wrong the maximilliam pionuses gets about 27-28cm (beak to tail), and for the purpouse of anyone correcting me that would be about 11inches. That means housed in sweden the smallest possible cage would be 120cm long and and 70cm deep (these two can change around a bit, ill explain more) and would have to be atleast 80cm high. I'll post the string with measurements etcetera I'm refering to:
Birds length: 26-35 cm
Smallest allowed surface: 0,84 square meters
Smallest allowed surface/bird, when kept in groups: 0,1 square meters
Long side has to be atleast: 120 cm
Minimum height: 80 cm
The short side of the cage is always regulated by atleast two times the birds lenght but never less than 45cm.
but then 28+28=56 and 0,56x1,2=
0,672 , remember it had to be 0,84... so 0,84/1,2= 0,7 wich means a cage that is
120cmX70cm is a minimum but same goes for a cage
150cm X 56cm (remember 2 times lenght is shortest you can go).
Now fortunitly you doesnt live in sweden so you do not have to obey these regulations, however I do keep my birds in cages the appropriet sizes and while it at first when i got birds felt silly I now feel its really good, its a good place to hang toys etcetera, it provides more room for enrichment and fun things to add to the cage for our fethered friends... saying this however I would never ever recomend a cage thats anything less than two times the birdies length in both directions. wich means I would definitly not go anything smaller than 56x56 for a bird that is 28cm long... but the bigger the better tbh. but a cage thats 40x40 I wouldnt go there with such a big bird... its less than budgies are supposed to be kept in... I do hope youre following my guidance through the math, and I am going to assume that you do know swedish and post a link to a decent page that sums up the birds minimum cagesizes on the other side of the border for ya
http://www.sverigestamfagel.se/Artiklar/Buren/burlathundSTF.pdfI hope this in no way comes across as nagging or in any way offensive (to you or any other user on the forum) I know these measurements for cages arn't implemented by everyoen who keep birds here in sweden and definitly not across the world... I do like that their there as a law and your supposed to follow em here since that ensures more birds has cages with enough room to play a bit etcetera in. I do have a brownheaded parrot atm in a cage smaller than what is required for them (couse she just moved in and i let her keep her old cage while settling in) but this cage IS smaller than what I used to have for my budgie but it IS bigger in all directions (except height) than the cage you posted measurements on. height isnt AS important as the other directions since their not really helicopters even though height is an added bonus. But to be quite frank I'd rather use one of the standard rabbit cages (120 X 59X 50 CM) and decorate over a narrow cage with alot of height to it.... anyways... enough about the cages, just had todo an opinion drop and hope to affect someone.
Well not quite enough... the most common reason for a smaller cage is either finances or space in the home, if space in the home... well then you might live too small to have a larger bird and allowing room to fly properly, if finances... can't really give you any helpful pointers on where to look in norway, but if your close to the swedish border/got possibilities to ship it to a friend in sweden and pick it up at their place, just send me a PM and I'll try help you find something worth buying for your feathered friend without emptying your pockets completely

Good luck and just post on here if you wonder anything just as you did, and I'm sure even more questions will arise once the feathered friend moves in with you.