Drain droppage - Maximum - Minimum - Precise?

It is my assumption that when a 1/4 in drop is stated that it means 1/4th inch for each foot. Is that correct?

I also assume that the drop can be greater and not be a problem. Although I expect the greater the drop the more water is needed to move the solids.
Am I right on either?

I am assuming the drop can be greater by my observation of my wall mount toilet. It appears to dump down straight through the wall to the pipes under the house.

When my house was built a wall mount toilet was placed in the full bathroom and a regular floor mount in the 1/2 bathroom. Both are at the same sitting height. So what would the advantage of the Wall mount back discharge be?

The liquid and solids fall at the same rate - gravity has that effect on things! On a typical sewer line, the solids get pushed along with each water discharge, they don't continue to the end on their own because of friction. Don't worry about it...just maintain at least the 1/4"/foot minimum, and you should be okay.