1)
あの夫婦のように is an adverbial phrase. It modifies the predicate. That couple might be old, and that interpretation would be more common, but the example sentence also can be used in the context like "they are still young, but have enough money and time to go round-the-world cruise". The main point is あの夫婦のように世界一周旅行してみたい.(I think this is more close to "when I'm old, I'd like to go round-the-world cruise like that couple" in English.)
Incidentally, 老後 often has a nuance of "after retirement".
2)
Another possibility; a typo of 姉は身じたくに時間をかけすぎだ.
4)
It simply means "the company's new product". Unlike a clause 同社の作り上げた新製品, 同社の新製品 is just a phrase.
However, I think more likely that the Japanese sentence has a typo, 同社が新製品を作り上げた, from the translation given. 同社の新製品を作り上げた suggests that the subject is not 同社; ~が同社の新製品を作り上げた.
5_2) b)
変わっていきます can refer to "changes that don't happen yet but will happen(can be guessed to happen) and continue into the future".