Head smashing was also present enough in episode 5x09 to give us reason to believe Negan is around. When Noah found his old house, he found his mother with her head smashed in the living room. Very similar to what Negan did to Glenn.
A trade-off is a situation where you make a compromise between two things, or where you exchange all or part of one thing for another. ...the trade-off between inflation and unemployment. American English: trade-off
The trade value is the amount of money the dealer is offering you for your car. They are essentially buying your car from you and this is the price they are willing to give you. The payoff is the amount of money you owe your financial lender to pay off your existing loan in full. During negotiations it is your job as the buyer to get the dealer to offer you a trade value that is equal to or exceeds the payoff amount.