Is money essential to long-distance trade, or does goods for goods (barter) produce more significance results in the
/long run?

No.

Explanation:

Goods for goods (barter) produce more significance results in the  long   distance trade because the traders sold goods and purchase other goods which wanted to sell in his region so there is no significance of money in these long distance trade, the people prefer barter system for them. In ancient times, people sell their items and purchase what they needed with the exchange of items.

well that depends on how deep the hole is. you'd first go through te crust of the earth, then the upper mantle, then the lower mantle then the outer core, then the inner cor then you'd be stuck in the core to melt.

confederacy: supported slavery, believed states should be able to nullify federal laws, supported low tariffs

union: everything else