Monks
Monk's Cafe was the name given to the diner in the show, but the exterior shot used for the diner is the real Tom's Restaurant in NYC. See the Wikipedia article in Related links. Monk's. Tom's Restaurant is the "real" NYC diner.
A rubber band
I think he ordered a 'bear claw' at the counter in one eposide
Toms Restaurant, known as "Monk's Café" in Seinfeld, was named after the show's co-creator Larry David's experiences at a diner in New York City. The name "Monk's" reflects a casual, familiar atmosphere reminiscent of a neighborhood diner where friends gather. The choice of a diner setting also allowed for the show's characters to engage in their iconic conversations over coffee and meals, which became a hallmark of the series.
Jerry Seinfeld's birth name is Jerome Allen Seinfeld.
His real name is Jerome Seinfeld.
Everyone knows on the show his mothers name is Helen Seinfeld. In real life his mothers name is Betty Seinfeld.
The diner's name was Frosty Palace.
True
They do not mention what the name of the diner was. They just say it was a diner in Philadelphia.
David Puddy's (From Seinfeld) real name is Patrick Warburton.
Jessica Seinfeld's birth name is Nina Danielle Sklar.