Questions about caching my site

Hi WP community,

Im thinking to cache my site using WP super cache and I have a question which is not clear to me yet…

If I change something on my front page (home page), let’s say at 12PM (Noon). Do the visitors of my site will see it that time or it will only appear after the caching circle completed?
Can I choose how often my site will be cache or the plugin is smart enough to see new content and then cache it again and delete the old cache?

Do you know what I mean?

It’s very confusing for me…

Thanks for any advise.