Launch Agents (User Level) - Background User Process

$ cd /System/Library/LaunchAgents/
$ cd /Library/LaunchAgents/

Launch Deamons (System Level) - Background System Process

cd /System/Library/LaunchDaemons/
$ cd /Library/LaunchDaemons/

This is basically like a cron jobs.Best examples of Launch Daemons are following plist files:
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Location: ~/Library/Keychain

Bash History file is very useful for investigation purposes. 
Location: /Users/<username>/.bash_history
- Usually it stores upto last 500 Bash Command but sometimes in live response/collection - you may get little more. 

• It's a hidden file
• It's only get created if user use Terminal App
• By default - There is no timestamp but you can add one please see this post: 

http://www.4n6world.com/blog/how-to-add-timestamp-to-bash-history-in-mac