When the average kinetic energy of the molecules goes up (a rise in temperature), the average speed of the molecules increases. And lower average kinetic energy of the molecules means they have lower speed. However, a change in average kinetic energy is not directly proportional to a change in average speed. 1.
An appreciation means an increase in the value of a currency. It means a currency is worth more in terms of foreign currency.
And the first thing you have to do, in dealing with economics, is get rid of the accountants. It's like getting rid of Claudius Ptolemy on the way to understand astronomy. The value of a currency is not its statistical average value today, based on exchanges. The value of a currency is its power.