Use numerals for numbers 11 and higher. This identifies the biennium as a special period of time and is an easy, visual method for making the distinction between the biennium and an academic year or a one-year budget period. He could not explain why, after mailing ten invitations, he received eleven responses back. Exclamation points and question marks can be either inside or outside quotation marks, depending on the sense of the sentence. Semicolons and colons are always placed outside quotation marks.
Essential clauses are necessary for the meaning of the sentence.
They are generally short clauses and do not need commas to separate them from the rest of the sentence. I have proofread the portions of the docket that were ready. The level of funding that was requested is adequate. Use which to introduce nonessential clauses. If a nonessential clause is removed from the sentence, the sentence still makes sense.