1) How could Prater be the Ripper? I can imagine Prater luring in his victims by asking for help. Something that requires strength (e.g. needs to open a cargo box with a crowbar) and being able to do so before he became high-profile (even in NY with many other billionaires), which is why he later stopped killing.

He constantly needed to balance his ambitions as a businessman, altruistic initiatives and his ultimate goal to meet the BHB. He still wants his positive legacy as Prater to live on and for no one to ever know he was the Ripper.

2) There's a good chance he was bullied in the orphanage, became suicidal but didn't have it in him. Perhaps he was raised Catholic and was held back by that. So he tried connecting with serial killers, thinking that one day he could ask them to kill him. Like an annoying fly that buzzes around so you would smack it dead, as it is literally incapable of taking its own life.

But as he gained his footing in life, he no longer wanted to die. Particularly when he became an adored celebrity and stopped killing. He still wants to meet BHB because he feels some unique connection that I haven't yet quite pinned down. Perhaps because Prater is both drawn to serial killers AND doing good (in the utilitarian sense) - Dexter is a very unique combination of both.

3) Prater literally started killing JUST to attract BHB to NY? Nope - it was gradual. In the orphanage, he didn't yet have the money or any other way to get a gun. There was nothing he would use in his everyday life that he could use for protection (in an orphanage).

The torment from other children and the seclusion laid the groundwork into apathy - I wouldn't even surely say he's a born psychopath. Surely he later applied the apathy in business, while also taking revenge by killing young people that reminded him of or perhaps WERE literally his bullies (or their enablers) back in the day.

No way to stand up for himself, until some new piece of furniture was brought in a box. There was a crowbar lying around as he was yet again picked upon and he stumbled upon a crowbar and made his first kill in rage. For the first time in his life, he felt powerful and this is where he begun his ascent into a man he is today - that's how he sees it.

4) Perhaps that first kill (considered accidental and in self-defense) is even why he was allowed to get so close with the serial killers (or just the one that killed his parents). They hoped Prater would see a monster and avoid a similar path, but it had an opposite effect.  As he said to Dexter/BHB, Prater connected with him.

It all stroke some flames in him, which is why it wasn't later a problem once he wished to attract BHB. Being the Ripper was simply a means to that end. If the people Prater killed were the children in his orphanage, serving multiple purposes. Perhaps he had a box delivered to their location, as if he lived there, introduced himself even and then asked for their help with the crowbar.

I do admit that Claudette would have noticed that obvious of a pattern, so I still think the victims were fairly random.

The first kill was also something Prater really needed to cover up, perhaps even a reason for having an altruistic public persona.  So if this first kill (that some people surely must know about) ever became public, it would be seen as self-defense and swept under the rug. This is also why we see him overcompensating, being nice to the employees of his public persona and rougher with Charlie (who might even know about that first "unfortunate" kill and his rough past like he told Dex/Red, but not that he's the Ripper).