Since the complex (and maybe "correct") way has been explained I will cover the second part of your question.
I hate math, I am terrible at mathematical formula in coding. This includes even things as simple as multidimensional arrays. This is why I was drawn to construct 2, with it I don't have to be good at complex programming logic to make some cool things. Now if I was planning on making a heavy loaded mobile game I might worry about efficient process but short of that I go with what works. I have learned a lot about the maths (and even array use) while doing so.
If "I" was making the game you are describing as a Construct 2 owner. I would do it the long hand way because it would be easier for "me" to understand and debug. My game making time is limited so I would rather be making progress than figuring out the correct way or efficient way if it is not needed for this project... by doing this I find I learn a lot of the correct/proper/efficient along the way.
I would make the three recyclable text boxes and a couple of variables for my holders and stats and I would then make a template (ie basically the first interaction with the 3 choices):
Set text box1 "It was a dark and stormy night, do you wish to go outside?"
Set text box2 "Yeah, sure why not? (Go outside)
Call function setTemp
Set text boxMessage to visible-Set text "Courage +&temp", "Dryness -&temp2"
Wait 1 - Set boxMessage invisible
Add temp1 Courage
Subtract temp2 Dryness
Set text box3 "Hells no!" (Quit game)
Function setTemp()
Set temp1 int(random(1-2))
Set temp2 int(random(1-3))
Set temp3 int(random(1-4))
Set temp4 int(random(1-5))
Now all I would need to do is copy, paste and change values for 500 events... would only take an hour or two.
If you were worried about event sheet length on older mobile devices then you could break your events up over multiple sheets but I would not think that necessary for most adventures.
As for the actual clicking process I would spawn invisible sprites under my text boxes that listened for clicks to determine what was the choice was. You could use long buttons as well that contain the text on them, but you would be limited to the Construct 2 ugly button.