You have the possibility to include these marks, and they are for finishing or postprint production and quality control.
Most printers don't print edge to edge and so it is normal to create a document for print with a bleed (I see from your document you have no bleed) on oversize paper and then is trimmed to the finish size. If you would attempt to cut your documents at the crop/trim marks you are likely to get a thin sliver of white (since you have no bleed).
Unchecking "All printer marks", or making sure none of the mark checkboxes are checked will give you the file with no marks. It does not mean that your printer can print to the edge of the paper, that is a limitation that you have to live with because the printer needs to grip the paper through the machine.
The grey bar is what is specified as Colour bars. The middle mark is the Registration mark. You should see in the preview these mark appear/dissapear as you check them.