Hey @jimdrury,
Regarding point 1, are you talking about On Demand ISR? If yes, you should probably follow this: Question - timeline to support on-demand Incremental Static Regeneration (ISR) on Netlify?. If not, could you please describe in more detail? Do you wish to purge cache for any URL on your site - regardless of whether it’s using Next.js or not?
Regarding 2, you should be able to utilize preview mode on Netlify. Can you outline what exactly isn’t working or where you are unable to enable it? Any error messages or additional details you can share would be beneficial for us to investigate this further.