My daughter, who is 18 yrs. Old, would like to change her father's last name to my maiden name.
Questions in regards to this topic:

1. How old she has to be (in NJ) to do this without parental consent?

2. Does her father has to be notified?

3. Will she be considered "emancipated" if she changes her last name?

It is expensive to change one's name officially in the court system for that is what it takes to make it official.

Your daughter could open a bank account with the ownership: Anne Jones AKA Anne Smith(your maiden name) and then, start calling herself Anne Smith while she saves up the money to officially change her name. That way, she can start calling herself Anne Smith going forward. She shouldn't screw up this bank account, needless to say.

Here in the UK we simply start using the name we want to be known as. But on official forms we may need to state other names we have been known by.