When I look at the graph of visitor times, should the local and server graphs be identical, except showing different times? Also, if I’m viewing visitor times at 4 pm for a given day (today), how can it show visitors for times AFTER 4?
Depending on the subject matter of your website and its intended audience, if your site is most popular in your own country, then most of your visitors will probably be in your time zone or nearby adjoining timezones, and so the local and server time graphs will look reasonably similar to some extent. However, you will probably still have at least some visitors from elsewhere in the world, who, depending on how far away they are, will add to the server time traffic levels at ‘atypical’ times compared to the bulk of your (more nearby) visitors.
Assuming a reasonably similar usage profile of all of your worldwide visitors, they will probably add to the local time (their local time) traffic levels at a similar local time to everybody else (eg, a peak at (local) lunchtime, whenever that may actually be compared to your (server) time). So it may be the case that local time visits are far fewer overnight (whenever overnight occurs from the perspective of your visitors) as most people are asleep overnight, but your server time graph gets somewhat smoothed/equalised as night-time occurs at different times around the world, compared to your server’s time.
As for visitors “from the future”, unless you and your server are located in Oceania or the far east of Russia, there will always be somewhere in the world where your future time has already occurred for them! 