Jewelry that is uncomfortable or jewelry that you make have an allergic reaction to should not be worn.
jewelry
The noun for the type of jewelery worn on the wrist is a bracelet.
Yes, it is. Apparel is basically anything that can be worn, or any type of clothing, and jewelry is often regarded as an article of clothing (most commonly necklaces).
No, the noun 'earring' is a commonnoun, a general word for any type of jewelry worn on the ear.
Jewelry is a kind of art that is intended to be worn. Clothing may or may not be artistically designed. Even make-up is in some cases a form of art. Tattoos are a type of art worn on the skin.
a dress
Crucifixes (being for Christians, a symbol of Christ's salvic death), should not be worn as jewelry (if by 'jewelry' you mean, 'personal adornment', ie something someone wears to be 'in style', 'cool' ect). For Christians, wearing a crucifix is an outward sign of faith in Christ, not a piece of adornment to wear because it reflects one's tastes in fashion/style.
Yes. Jewelry stores have mezuzot you can wear as pendants.
Typically Roman men wore less jewelry than their female counterparts. Finger rings and fibulae were the most common forms of jewelry worn by men, but they would also sometimes wear pendants.
Ring
The bracelet.
Whenever you wish