well by way of comparison, The Inexorable Search works by running your finger over a map and letting you sense when to stop, that is when you are pointing at the part of the map that corresponds to where the body you are searching for is. A super strict reading of the spell guidelines might demand that this is an imaginem requisite since you are receiving a sensory information, however the spell in the core rulebook has no such requisite and I think we can safely assume that this means such small pieces of flavor can freely be included. Notice also that the spell is kind of reading what is on the map as if the map is an arcane connection to the terrain or something or perhaps the spell is reading the map in a very intelligent manner. So you probably have quite a lot of leeway in what ways the information can be delivered and how the spell can play out.
But looking at your spell it is very unclear to me exactly how the information would be delivered.
Imagine a simpler spell that learns the height of a single man (you seem to use height and size as if they were synonymous). but we really need to describe the spell a little more precisely, so I will have a go at it:
What is the height?
InCo level X (level really does not matter for my example)
Range: Voice, Target Individual, Duration: Momentary.
The caster points at a target within range and learns the height of that person, the information just pops into the mind of the caster as a height in whatever measuring system the caster is most familiar with.
This description is kind of key to understanding whether or not the spell you are trying to create is valid. I would argue that the spell I have proposed is a valid spell based on the guidelines. It could even be generalized to a boundary spell if you are so inclined (which I assume you are).
However if your spell description had read something like:
Different what is the height?
InCo level Y (level really does not matter for my example)
Range: Voice, Target Individual, Duration: Momentary.
The caster points at a target within range and learns the height of that person, the information appears in writing on the nearest mirrored surface
Then that spell would at the very least require an imaginem requisite and even then the spell is kind of weird because what happens if the nearest mirrored surface is far away, say that it is the surface of a still pond several miles from your current location. Did your spell just target that surface? does the spell fail if there is no mirrored surface within voice range? lots of questions.
Notice that both of the spells I describe above use the same basic guideline (the one you suggested about determining a single fact about a single body) but one spell is very straightforward and the other is a nightmare to arbitrate.
A lot of your questions seem to revolve around what constitutes legal flavor text and that is very difficult to answer in general terms. Perhaps it would be best if you would attempt a write up for the spell/power you are thinking of and the debate continue from there?