Trade in and buying

If you trade in a crapper they might give you $500 but be aware that they probably will raise the price on what you buy. In my opinion trade ins are mostly a scam where you get a fraction of what the car is worth and they then make up for it by not giving you a fair shake on the selling price.

Depends on the dealership, shop around.

Make the deal and then tell them you have a trade in.