They either place component with top and bottom touching or left right touching, or not touching at all.
Is such box available in Kicad? This box has a name?
Yes, it is no fun to go too small unless necessary and the factory can support it at their low price offering showing that it is mature tech for their setting, easy and high yield.
I’m not sure what you’re asking. Most components in KiCad have a silkscreen outline, but very small resistors and similar components don’t, simply so you can place them tighter together (if you want) without the silkscreen colliding with adjacent pads.
If you also want silkscreen on tiny resistors, you have to copy and edit the default footprint.
Make sure the silkscreen is far enough from the pads to not cause problems due to printing tolerances and so on.
I have to admit, though; using this method is a pretty neat way to measure the size of the courtyard. After drawing the courtyard, drop the clearance to something more suitable.
I’d never thought of this: but that doesn’t mean a great deal.