What do I use for the Path to the Craft folder?
You will definitely want to put it above the root even if it's an add-on site, in which case the proper setup would be '../../../../craft' but this would generate a conflict with the main site craft install since there would be two folders with the same name above /public_html, so you could rename the add-on site craft folder to craftaddon and than the path would be '../../../../craftaddon'. 

In case there's a really good reason for leaving it below the root, you would just use '../../../craft' but that does come with security risks that are pretty much not worth taking.