matamune just messaged me about the first question, too. Yeah, Cat Viper's line from VIZ is less vague than Mangastream's; he says "And it's only been a few months since then. I suppose the liveliness of those folks has been a blessing to him…" I'm guessing maybe he's talking about it being a few months since something happened to Oden (Momonosuke's dad), and that the Straw Hats' liveliness has been a good thing for Momo. In that case, yeah, I'd guess whatever happened with Oden happened a few months ago and the samurai group fled after that.
For the second question, someone made this post on Oro Jackson that sounded like a great explanation:
@The_Monster_Trio:
Guys, I solved the mystery of Zoro's strange call to Raizou "Hide in the ceiling and get pierced by a spear"!
I already found the phrase strange when I first read it, because it was too specific just to be random talk.
So I did some research and found that it relates to the Ninja called Kubo Uemon, whose story is told in the Bansenshukai,
an historic japanese book about the Ninja and their ways, often called "The Bible of Ninjutsu".
In there is a story about this ninja. In short, he had the mission to infiltrate a certain family's house, and manages to sneak himself in, and hid on the loft. But, at night, when he decided to move, someone was still awake and heard him. Then this person woke the master, who took a spear and stabbed it through the bamboo ceiling at where the sound came from. The spear hit Kubo's forehead, but he immediately grasped and wiped it claen with his sleeve before it was pulled back. The master concluded that what he hit couldn't be alive, as there was no blood on the spear's neck, and thus there was no threat. After everyone went back to sleep, Kubo Uemon came down and stabbed all the residents to death.
But, he retained a scar from the spear. This is especially interesting, because Raizou also seems to have a scar on the same place.
Look at his forehead:
Interesting to find out what kind of books out Goda reads in his free time
And he even takes the time to include references in his manga.
He's putting so much thought into One Piece and that's what we love him for!
But it's not like pop culture references are new to him
We'll see if Raizou's scar has a special meaning or backstory, too
Looking forward to the next chapters!
Hope you enjoyed this (long) bit of background interpretation
Credits to Oro Jackson member The_Monster_Trio for the above quote.
For the third question, I think yes. At the very least, we know Roger can, and this chapter heavily implied the same for Momo and Oden. Has it been confirmed for Luffy yet? If it hasn't, I hope it will be.