I have already created a few ideas to add to national focuses. How do you find the code name for the ideas so you can add them to the focuses?

Also, I want to make the idea a timed idea (i.e. 720 days) so where can I do that?

The reward for the focus would be:

add_timed_idea = { idea = YOUR_IDEA  days = NUMBER_OF_DAYS }

For example, with the "Bad Economy" idea in your "World of Differences" mod:

add_timed_idea = { idea = CE_bad_economy  days = 720}