What's the difference between 让, 令 and 使?
让 is frequently used in speech, usually translated with &quot;to make somebody do something&quot; or &quot;to let&quot;. Your other examples illustrate it nicely.

让我想一想 (= let me think a bit)

The most fundamental difference between 让 and 使 is that 使 means basically &quot;cause to&quot;, therefore it's used mostly when it refers to inanimate entities or when there is no intention.

山火使空气严重污染 (= wildfires cause the air to become heavily polluted)
中国经济增长使新西兰获益 (= China's economic growth causes New Zealand to profit)

You can of course translate that more liberally, but the basic meaning remains.
Note that 让 can some times be used with inanimate subjects too. I see that as a colloquialism.
令 is more formal, but used in speech as well, mostly in constructions like 令人X where X is some phrase denoting feelings. Your understanding is correct.

令人吃惊
令人愤怒
令人印象深刻