Well, this is certainly news to me, as I assume it is to most people. A google search turned up nothing on this. What is your basis for these 2 claims?
It is good to read books, too. Rehwinkel - The Flood, published by Concordia Publishing House. That book is dated but has plenty of interesting information.
"Every culture has a story of a family surviving a global flood...(&)... October 31st is a day of death celebrated by cultures all over the world." (vs) "..news to me, as I assume it is to most people...What is your basis for these 2 claims?"
It's been a long (!) time since I read much on these things but the original post is not necessarily amiss.
Just about every culture I've read about DOES have a catastrophe tale/story/myth (whatever) that involves displacement, rigorous survival, and divine intervention: certainly the survivors are considered righteous unless proved otherwise by that divinity. Whether "the people" (ethnocentric yes / racist no) are forced up from their peaceful underworld, driven south by fire or ice, or put in a boat for a month, the fundamental story is pretty much the same. The idea of a wise and righteous man having saved livestock and seed/plants for the generations that follow a regional catastrophe also fits.
I don't count on October 31 being universal in itself but the onset of winter, end of the crop cycle, potential for starvation or at least extreme cold, is still felt everywhere there are seasons: it was a time of quite literal fear to early humans. (Los Angeles and Aspen being exceptions for very many reasons - only one of them being that early humans probably avoided both.)