There is a 1 hour timeout for entities that are marked for deconstruction - this was done for performance issues way back around v0.12.x from memory.
I have issues with this feature, because I plan and place ghosts a lot, and this feature messes up things like on the video below.
All I want is an ...

I support this idea. This should have a toggle option in settings.

There should be ghosts that robots won't build. Ghosts are a very convenient planning tool, but when it comes to planning something with ghosts in a robot-controlled area, the robots start building all the ghosts you've placed, which ruins everything. We should have personal ghosts, sort of "for ...

There must be a possibility of pipe-dragging like belts, including pipe to ground auto-building like underground belt.

We must be able to place train ghosts on rail ghosts and also see ghost rail blocks (when placing a train stop or rail signal on it)