I feel a little tangled in grammatical nuances and would like you to help me clear some things out. I know it's possible to use either the past simple, "used to" and "would" to talk about past habitual actions. But is the use of the last two of them limited only to personal experiences, or is it also correct to utilize them while talking about, say, historical events?

In other words: do these sentences mean exactly the same thing to you? Do you sense any differences between them?

> 
> 1. Jack the Ripper approached/would approach/used to approach his victims slowly and nonchalantly.
> 2. The Aztecs fought/would fight/used to fight their enemies with wooden pikes.
> 3. When he was a boy he practiced/would practice/used to practice playing piano.
> 4. I read/would read/used to read a lot about astronomy even during my childhood.
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I know a lot of such cases depend on the context; past simple can mean both a specific action and a series of repeated events, right? Oftentimes it's the words that create the meaning, not grammar, but does it apply to the utterances listed above?