Good Riddles

Question: Something different to show every week, but I'm still the same place.
If you're eating it's probably butter that you taste.

What am I?

Question: A man wants to buy a used car. He finds a beautiful Buick for $9500, but he buys it without paying a dime.

How did he manage this?

Question: Christmas and New Year's Day occur exactly one week apart. So a New Year's that occurs right after Christmas should be on the same day of the week. But in the year 2020 Christmas will occur on a Friday and New Year's on a Wednesday.

Why is this?

Question: A young woman is attending her mother's funeral. While there, she meets a man she has never seen before and falls in love immediately. After the funeral she tries to find him but cannot. Several days later she kills her sister.

Why does she kill her sister?

Question: Walk on the living, they don't even mumble.
But walk on the dead, they mutter and grumble.

What are they?