I don't think its wrong to ask as long as you do truly sound curious. People who get scoffed at about it usually ask about cultural things in demeaning ways. I once was asked, "hey I saw on Indiana Jones that Indian people ate money brains, do you guys really do that?"
As for the silver bracelets, it depends on whether they are Punjabi. Sikhs wear a gold (plated) or silver bangle on their wrist. Also, Indians in general love Gold, so that could be part of it
The Bindis were traditionally only red and made of a powder and worn by women to show they were married. One of my grandmothers stopped wearing it after my grandfather passed away. But like Jasepl said, it's lost its significance since the last generation and are now mostly worn as an accesory. They also come in different styles too.
"Look Lois, the two symbols of the Republican Party: an elephant, and a big fat white guy who is threatened by change."