Hm...

Well, Glowing auras, yes. Brighter wherever it's more concentrated up until a point where it just kinda... Well, stops getting brighter.
Color's usually determined by specialization, if at all; unaffiliated (purely physical) is translucent, lightseekers are blue, soulbinders are red, and naturalists are a mix of yellow and whatever is the color of the soul they're bound to. Else, if it can't be manipulated, it's usually this mishmash of light across the spectrum. Really faint.
And... Well, yes, strength can be eyeballed to a fault. Depends on the strength gap or something to that extent. Like how you can't tell the difference between a termite and an ant from a human's objective viewpoint.

I'll get more details hashed out tmrw, if necessary.