Thanks to the wonders of modern forensic analysis, it seems we might finally have the answer to at least one of these questions. As reported by USA Today, CBS News, and The Sun, a silk shawl belonging to the Ripper's fourth victim, Catherine Eddowes, was found to be saturated in DNA belonging to Aaron Kosminski, a 23-year-old barber who at the time both lived in the area and was one of the police's top suspects. That's right! It took us over 130 years, but we've finally narrowed the suspect pool down to ... the guy who a lot of people thought it was from the beginning.
Except it's probably worth pointing out the myriad problems with this study. The biggest being that the science used doesn't actually "prove" anything. The biochemists who conducted the study took the mitochondrial DNA (mtDNA) present in a supposed "semen" stain on the shawl, and matched this with a mtDNA sample provided by a relative of Kosminski. But as Science points out, mtDNA isn't a reliable means of narrowing down a field of suspects. That's because the same mtDNA sequence can be passed down through countless generations, meaning that mtDNA isn't a unique marker in the same way that "normal" DNA is.
Kosminski didn't pass his mtDNA signature to his descendants, because mtDNA can only be passed through a maternal line -- meaning that Kosminski got his mtDNA from his mom, who got it from her mom, who got it from her mom. The best thing that this analysis can say is that Mr. Ripper descended from someone on this long, long line. The "semen" could've com- uh, originated from Kosminski ... or from any of his countless distant relatives who might've also been wandering the streets of Whitechapel.