On Ask Ubuntu, a user asks a similar question (albeit its on Ubuntu, but it should apply to Mint).
Here is the Link: https://askubuntu.com/questions/621677/what-does-inactive-mean-in-suspend-when-inactive-for-xxx-mins
Alexis Wilke (the guy who answered on Ask Ubuntu) says that being inactive is considered when no user interaction takes place, such as moving a mouse, pressing the mouse or pressing a key on the keyboard.
He also says that when there is network traffic, that may be considered as user activity. (though not too sure about that one)
Tim comments and asks if that there was a backup, would it still suspend. Alexis goes on to say disk activity is not considered user activity, so it would suspend. He also says that some backup systems can prevent the machine from suspending itself.
Now, to answer your question:
- It would probably suspend after 5 mins, since you're not offering input.
- A script from the terminal would probably be suspended after 5 minutes, since you won't have any input apart from executing the script.
- Automatically refreshing a webpage would be considered user activity as it requires a mouse click or combination of keys. It would not suspend then, even if the clicks are simulated, I believe it still counts as user activity
- If you stopped using the keyboard, well, that depends. If you stop using both the keyboard AND the mouse, it will suspend after 5 minutes. If you use the mouse but not the keyboard, then no.
I hope this helps. If anyone finds my answer incorrect, you're welcome to edit!