If it closed August 1st, the corporate due date MIGHT be November 1st (the current due date for a C-corporation with a fiscal year ending on June 30th is 2.5 months after the end of the year). I'm not 100% sure if that applies for a 'short year', but I would recommend filing an extension by November 15th just to cover it.
https://www.irs.gov/pub/irs-pdf/f7004.pdfYes, a 966 should be filed. Even though it is late, I'm not aware of any penalties unless it was INTENTIONALLY filed late.
