I can't find any information on how to rename the section titles, particularly the one called 'Tax Location'. I would like to simply rename this to 'Address', since I won't be collecting any tax. How is this done?
You can try this: https://s2member.com/kb-article/quick-translation-changing-wordsphrases/
Did you configure the taxes setting at all to make those fields appear in the pro-form? WP Admin > s2Member Pro > PayPal Options > Tax Rate Calculations
This post may also interest you: https://www.s2member.com/forums/topic/tax-calculation-on-reg-form/index.html#post-14411
I hope that helps.