I'll answer some of your questions to the best of my ability. If anyone else has some answers, we'd appreciate it!
1. Harpo died September 28, 1964.
2. Harpo was cremated.
3. Harpo's harps were donated to a university in Israel so the harp students could play them.
Some of his paintings are still in the family, while others are owned by people Harpo gave them to. Since that was now many years ago, and some of the recipients have passed away, their belongings are being sold. Every now and then you will see one of Harpo's paintings up for auction, even on eBay at times. Not very often, but it happens.
4. Harpo wrote the music to "Guardian Angels". The words were written by Gerda Bellenson.
Harpo also wrote "Lullaby Doll", and "Harpo Woogie".
5. Harpo was born November 23, 1888. My guess is that they all shaved off five years to appear younger, since they were in show business. I don't know if this is true or not, but I heard that in the early days Minnie made their ages younger so they would still get the children's rate when they were traveling by train.
Yes, let's all pay tribute to Harpo on this day, the 40th anniversary of his passing.
We love you Harpo!
Regarding Harpo's age, in his book he said he was born in 1893. On a site I saw, someone scanned in an article written on Harpo's death, saying he died at 70. Unless my math is off, that puts his birth at 1893, like he said it was. Whatever it is, Harpo will still live on as long as someone remembers him.