Numerus “Numerans-Numeratus”
1. Anything that is abstract...also has an abstract space. There is an abstract unicorn...it is abstractly 2 feet tall. The length and width of abstraction is arbitrary...as stated in the op. I think you might have mis-read the op. I had said...let all abstract width and length remain undeclared.
2. Zero is given a dimension for many reasons. All of which are philosophical...
2a. Nothing can NOT exist: therefore 0 can not be nothing.
2b. All that exists is either space or value, 0 is not value, therefore it must be space.
2c. Assigning a dimension to zero is the process that allows for division by zero.
I may go on but will wait and see is you agree...
Lastly there is a great difference between 0 seconds, 0 centimeters, and so on....
In all cases I have 0 of the thing given....but in no case do I have nothing....therefore varying amounts of zero, or alternatively. I may have two cups before me, both empty...but of varying size. Therefore varying amounts of zero. There is more space between Jupiter and the moon, then between the moon and earth. Therefore varying amounts of zero.
I hope I have answered all of your questions sufficiently. Thank you for you time.