If I buy a stock before the ex dividend date but sell off before the record date and pay date, will I still be entitled to dividends? Thanks.?

I'm not sure what is your rationale for doing that because in theory, this may seem like a great strategy but in actual fact, the stock price would have declined in value by the amount of the dividend after the ex-div date. Unless you are thinking of holding this stock for the long-term, I really do not see any point in doing that.

Yup you will still be entitled if you buy before the ex dividend date and hold till the ex dividend date.

You can sell on or after the ex dividend date and still entitled to the dividends.