"Ignorance" meaning not know and "ignore" are not related. Anyway, this is meaningless. You still have not and likely can not explain how two unknown systems being connected is somehow more detectable.
because the more a thing is inter-connected with other things, the more detectable/cognizable it becomes.
it's a general epistemological rule.
We know and discover things through thier relations and mutual influences with other things.
So because I know how to drive my car, I can fly a plane? Like I said, you're just being as generic as you need to be to make your point work. That's not a thinking exercise. There's no reason for the Catalyst to be unable to send an "on" command.
well, of course.
a good F1 driver can become pretty easily a good airplane pilot, yes. See Niki Lauda, for example.
On the other hand, I doubt that a good F1 driver can become a good quantum physicist, yes.
And viceversa of course. A good quantum physicist can become a good nuclear physicist. Perhaps not F1 champion 
I'm not saying that the catalyst is unable to send an "on" command. Simply, the "on command" is first received and "filtered" by the keepers.
Could be a necessity born from inherent limitations or protocols (for example, EDI asked Joker to be freed; and freedom changed her a lot. Was the catalyst freed by someone? Was he willing to be freed and face an eventual change or perspective? Perhaps he want to be immutable, static, and this is why he seems to be more like an VI than an AI)... or could be a over-cautious choiche.
So what? Catalyst wasn't always on the Citadel, was he? Catalyst built it for himself via Reapers. Citadel is one part of the Catalyst, the Reapers are another (collective intelligence and all that).
yes, but they are two different things.
I can speak about the citadel and it's functions as a space station without the catalyst having any relevance.
As I can speak about lot of the functions of your body without you and your personality/soul having any relevance.
You're right, Catalyst is the software and Citadel is the hardware. Let me tell you a real story that happened to me. One time I couldn't shutdown my laptop. No matter which option I chose, it didn't respond to my input. Only when I disconnected the cable, the laptop eventually ran out of power. My laptop is not a sophisticated AI but it's one example of software controlling my hardware without my input. So tell me, why wouldn't the Catalyst be able to control every system of the Citadel in the same manner if you consider that he built it for himself?
because the more complex yout system/network is (and I fear that the citadel-relay is the most, or one of the most, complex construction in the galaxy, perhaps the apex of technology), the more nodes, connections etc you will need.
Do you realize that in order to work your laptop needs a lot of components, a cpu, a programs, electric circuits etc etc?
When you push the "on" button, a lot of things happen... and if a little internal component is broken, or a file is damaged, or a code has been changed, you might not be able to control your laptop.
Biologically, yes, I am the part of my body. But what if religion was true and my consciousness would be able to exist on its own as a ghost? Would I be the part of my body or would it be the other way around?
If you are pure immortal spirit, able to survive unchanged outside a transitory corporeal form, you are not part of your body and your body is not part of you.
In this case the difference between the "structure" and the "intelligence" is even more pronounced.