Nothing, unless your statement cuts that night.
Some creditors use the statement closing balance when reporting to the credit bureaus. So you could see your score drop when your utilization goes up. However, assuming you don't redo this monthly, your score should jump back up the next month.
If you don't have a good payment history with the creditor or pay the minimum payment they may choose to close the account. However if you are paying on time and the balance in full each month then you shouldn't have anything to worry about.
It may reduce your credit score as it shows on your credit as using lots of your available credit.
Do you mean max out, or go over the limit? If you simply use up all the available credit without going over the limit, and pay it the next day, nothing will happen. As long as you pay your credit card off every month, you will not incur a finance charge.
Nothing in particular. It isn't using most of your credit limit and paying it off that same month that hurts your score. It's carrying balances that can negatively impact your score. As soon as you pay off the balance, you score rebounds.
Using that much of your credit limit DOES negatively impact your credit score because the card issuer reports the high balance every month and your debt usage level is very high. This reduces your credit score.
Nothing
You will have an available credit to spend again.