...and here are the remaining settings and functions that do not fit under one of the other headings, especially from the setup menu.
The setup menu lets the image sensor vibrate briefly to shake off dust in the truest sense of the word. This works best when it is standing upright.
It's worth a try if you find little specks in the same place over and over again on your pictures. However, it is doubtful whether cleaning will do any good, because the D5100 is preset to start it every time it is switched on and off.
If the menu does not help, the only option is conventional cleaning directly on the sensor. You can do this at Nikon, at your local specialist shop or carefully yourself if you know what you are doing.
You can also set whether the D5100 should automatically shake its sensor briefly every time it is switched on and/or off. I leave the default setting, it can't hurt.
This setup menu is for maintenance purposes only. It folds up the mirror and after removing the lens you can look directly at the sensitive image sensor. Only when the camera is switched off does the mirror fold back again.
If the battery is not sufficiently charged, the menu cannot be opened.
Setting the date & time, time zone and summer/winter time.
For the semi-annual time change, it is sufficient to set the summer time to on or off here, and the time jumps forward or back by one hour accordingly.
Choose the language for all camera menus here.
Allows to create a reference image for removing dust in Nikon's Capture software.
Shows the version numbers of the camera's internal software. The best way to check whether yours is up to date is to visit Nikon's web site. There you will also find updates and instructions for updating. I would get updates only from there.
If your firmware is not up to date, don't worry. Most firmware updates only bring very small changes. I would then read Nikon's explanations of the updates and only install them if the update promises improvements that are useful to me.
The setup menu controls when a connected separate GPS receiver switches off and allows the current longitude and latitude to be read out.
The playback menu creates a file on the memory card for making paper prints.