Yesssss! It's a holiday from reality:) you can be who ever or whatever you want to be that night. Unfortunately you don't get paid leave from work though :/ I think you should. Halloween is awesome :)
Can Halloween be considered a holiday?
Sure - why not.
It is actually a Christian holiday, it is called All Hallows eve, or in the Catholic church it is also called All Saints Eve. Some countries, especially Catholic countries, have a day off from work to celebrate. It however is not a US recognized holiday.