1. The most powerful bosses of the Genovese Family were Vito Genovese's two predecessors: Charlie Luciano and Frank Costello. Luciano formed the Commission and became the de-facto Capo di Tutti Capi until he was convicted of Mann Act (white slavery) violations in 1936, sent to prison and exiled. Frank Costello, imo the most successful and powerful Don in NYC history, ruled from 1946 to 1957, when he was wounded on Genovese's orders and retired. You'd think Vito Genovese would be the most powerful because he forced Costello's retirement. But Genovese's reign was short-lived: he was set up in a drug deal in 1959 and sent to the Atlanta Federal prison, where he died.
2. I believe you're thinking of Angelo Bruno, the "gentle Don" of Philadelphia, who had ties to the Genovese and Gambino families. But he wasn't whacked by NY families. He was whacked by his own consigliere after he declared Atlantic City an "open city" to prevent a Mob war. He was actually protected by the Genovese and Gambino Families earlier, and Carlo Gambino was responsible for his becoming Don of Philadelphia in 1959.
3. Valachi claimed that Vito Genovese gave him the "kiss of death" when they were in the Atlanta pen together. He then became paranoid, and bludgeoned to death another prisoner whom he thought was on a mission to kill him. Did Genovese really give him the deathkiss? I don't know. Valachi may have started singing because he realized that he'd killed the wrong man, and saw singing as a way to avoid the death penalty and get better treatment. Again: who knows?
4. The Chin certainly did walk the streets of Greenwich Village in New York in his pajamas, talking to trees, being led about by underlings, etc. He was successful enough in this ruse to avoid being tried under the same RICO full-court press that sent three of his fellow Dons away for life. But, as you probably know, he recently was declared compos mentis by a judge, sent to jail, and even more recently, pleaded guilty to having faked non compos mentis, which helped keep his current sentence manageable. The good news for him is that he succeeded in not being sent away for 99+ years. The bad news is that, despite his humiliating sham, he's gonna die in jail anyway.