Freshwater bath/ Qt

[Ian]

As I now have rock and water in my new set up i need to start to ask questions about adding livestock and QT.

First- Is a freshwater dip a must when adding new fish/corals? I have not done this with my BC and want some info/opinions.
If you do use a dip what process do you use?

QT- how long should it be?

Last do both need to be done or can one replace the other?

thanks to everyone in advance for your input.