If you are asking about a street address, both words are in capitals
The phrase "Columbus Day" is the full name of a holiday. Therefore, both words should be capitalized.
The way you capitalize other words. If it's at the beginning of a sentence it should be capitalized. If it's not then it shouldn't be capitalized.
If you are using it in a title.......... How I Spent My Summer Vacation.
Voodoo must definitely be capitalized since it is a religion. The same way you'd capitalize Roman Catholic, Jewish, or Protestant.
No, the word is not capitalized.
Yes, you should capitalize the "N" in "I-75 North" as it is the correct way to indicate direction on a highway or interstate.
Yes did correctly I believe you want to capitalize the word day as well: Martin Luther King Day.
I believe the word is capitalized when used in reference to a specific king, e.g. King Henry, because it is rightfully that person's title. When used in reference to kings in general, e.g. the king of England, it need not be capitalized.
The correct way to capitalize the sentence is: "My favorite novel, The Adventures of Huckleberry Finn, is set mostly on the Mississippi River."
No, not unless it was beginning the sentence. Capitalize, by the way.
The proper way to use this would be: Your friend, : )
No you don't capitalize university unless you have the name of the university, like University of Texas. It's the same way if you say school you only capitalize school if you add the name of the school afterwards, such as Woodland school.