Standard style and usage says that you do. This has not always been the case, however. There are examples from the King James Bible where the interrogative is used in mid-sentence with no upper-case following it. If you want your writing to appear professional and competent, use the interrogative to end the sentence, and start a new one with an upper-case letter.
If you are referring to the planet, then yes, you should capitalize it, as you would capitalize Mars, Jupiter, Pluto, and other planet names.
If you are referring to the brown stuff underfoot, then no, you do not capitalize it.
As a general rule, you capitalize proper nouns; that is, nouns that are names applied to unique things such as: London, Abraham Lincoln, Earth, etc..
No, except at the beginning of a sentence because it is not a proper noun.
You always (no matter what) capitalize the first letter of a quote.
No, you do not. Only the beginning of a sentence should be capitalized. For example, There was a time in my life when asking "mommy, what does that mean?" was very annoying to my parents.
Thank you
Your question is inconsequential, considering Bansky himself (or herself) created the intro.
Are you kidding me (question mark).
Like this. "?"
What an 'envalope' is (question mark)
If you are talking about the question marks in the pokedex, then you have to catch them, trade them, or find an action replay code. If you need more help on where to find them, go to www.serebii.net.
Yes you do.
Yes you should.
Yes, 'Is that a duck face that I see?' is a correct sentence if you capitalize the pronoun 'I', separate the word 'duck face', and be sure to put a question mark at the end (I realize that the question box wouldn't accept the question mark in the middle of the question, but it will allow you to capitalize in the middle of the question).
The pronoun "I" should always be capitalized.
Yes, "Flag" should be capitalized when referring to the American Flag, as it is a proper noun.
Who is your favorite French artist (end with question mark).
Yes, you always capitalize "Cuban."
No. A question always has to end with a question mark.
Because that is how to punctuate a question properly.
The explanation point is always before the question mark.
"Who is your favourite French artist?" (Note, the quotation marks are there as without them, the question mark flags the answer as being a question - which is not allowed in Answers.)
If you have a Latin (make sure you always capitalize Latin) set then you always read/write in Latin.