They're published in a big book called the "Enchiridion of Indulgences"; "enchiridion" being the Greek equivalent of "handbook".
How do you keep track of what you’ve paid in?
God does that. But what do you mean by "paid in"?
When do you know if you’ve done enough?
Enough for what, exactly?
How do you know what your paying for?
There's that term "paying," again. Where does payment enter into it?
How does the individual believer keep a balance sheet so he knows what his endulgences are accomplishing?
Did God write the Enchiridion?