You do not need to create a table of contents manually. If you use headings, an automatic one is created for you and available in the right sidebar!
How can I create a running total in a table?
Your formula will need to live in a different column to the values you wish to sum.
How can I add a timestamp at any arbitrary time point? For instance, if I want to add a timestamp for 19:00 while I'm at 20:00, how can I do that?
In a text block: type +timestamp and hit enter.