If you are trying to be all formal about it, it's good to start by defining your terminology. What do you mean by Consciousness and what do you mean by existence?

I'm trying to be slightly formal, but without getting too bogged down. Instead I would prefer to take a few shortcuts to see if the road ahead looks promising at all. So far I feel that the best I've managed is to say "If a system seems to itself to experience consciousness in the same way that we seem to experience it, then we can call it conscious".

I am pretty sure you have no firm understanding of what you are talking about,

Not as sure as I am ;-) But I am trying to improve my understanding, and have no intention of writing philosophy papers.