First question: The "'d" can stand for "would" or "had." As mentioned in the comments, your first example uses the "'d" to stand for "would," which can be a conditional ("I would go to the movies if anything good were playing.") or an equivalent to "used to." ("When I was a little boy, I would buy an ice cream at the corner store every day, even in the dead of winter.")
Second question: The narrative of the paragraph is set at the time Rudy was a middle manager at Standard Oil. The action "He'd emigrated from Germany" also took place in the past, but earlier than the setting of the paragraph. In other words, you are explaining how he got to America to be a manager at Standard Oil; you are backtracking in time. That is the correct usage of the past perfect (had + past participle). The simple past ("he emigrated") is just an action set in the past without any such backtracking. That being said, many native speakers of English use the simple past in place of the past perfect in casual conversation ("He emigrated..." in the paragraph you gave). This is not considered a grievous error, but should be avoided in formal writing or speech.
Third question: The present perfect ("He has emigrated") can be shortened to "He's emigrated." Note that the "'s" stands here for "has," but might stand for "is" in other constructions; i.e. "He's waiting."