The way I see it is that they glow the same as if sustaining the spell through a focus, or the same way an adept glows when they have improved reflexes, STR, AGI, etc. all active at the same time.
I don't know. That is a valid interpretation of the rules, yes. One could say that it takes a few assesning successes to understand what makes this mage's aura interesting to look at - as many successes as it would take to figure out an adept's power point choices, for example.
On the other hand you could rule that each sustained magical effect is like extra foci and sustained spells are can be assesnded independently, making them more obvious.
Word of God would be nice, though.
That said, this is talking about a Combat Mage trying to make sure they can hurt people more. Stealth probably isn't their skillset.
Most runner mages also run errands, walk the dog, seek rest and relaxation, and go about their lives in their off-time, too. The Troll Street Sam knows better than to carry her assault cannon everywhere because it might draw the wrong kind of attention.