What are the money-changers doing in the temple, and why did the "Jews" object in John 2:18?
At first, people brought their own animals and the priests inspected them to make sure that they weren't sick before sacrificing them. Fast forward a few hundred years and the priests were telling the people to leave their animals at home and instead just come and buy animals at the temple to sacrifice. But there was a catch. Since priests couldn't touch coins that bore the Caesar’s image, the people first had to change their money, for a fee of course, into a special temple money. So the priests were making money twice - the currency conversion and the sale of animals - on each person and didn’t appreciate Jesus crimping their business.
Does anything like this ever happen today?
It happens in every religious organization in which the leaders live in luxury from the monies collected for God's work around the world. The tactics may have changed but profiteering in the name of God hasn't.
Where does the Bible say the judgment will begin?
According to 1 Peter 4:17, "house of God".
What’s peculiar about what the Jews said in verse 18?
They actually are not saying that what Jesus did is bad. They are simply asking him to prove his authority to do it.
What does Jesus say in response?
His resurrection will prove who He is. The resurrection of Jesus confirms His deity. If there had been no resurrection, Christianity is one big waste of time.