Your professor is stuck in the past; the days of a double-space after a period are long gone.

I would also like to object to the terminology of the last question in your poll; the rule against beginning a sentence with a conjunction is widely believed to be rubbish. Fowler calls the rule an "ungrammatical piece of nonsense," and the view seems to be that so long as the sentence beginning with a conjunction is a complete clause, it's okay. However I wouldn't begin a sentence with a conjunction in formal writing.