We know the Princeps was killed at First Calderon. It's mentioned more than once. So, anything about when the Princeps died would tell us when First Calderon was.

As for when Tavi was born, about all we have to go on is what Isana and others say. My guess is that Isana tells Tavi a number, then Tavi takes her at her word. So if Isana lies, nobody else knows (except for Gaius, I expect).

Dead, probably. Curiosity killed the mortal.

I'm looking at this, and I'm having a hard time making heads or tails of the system from the preview.

Except that Harry apparently does have a decent layman's understand of technology.  If you'll recall, the GPS is Harry's idea, because he read about it in magazine in the library.  So while Harry certainly wouldn't have much "hands-on" knowledge about technology, it appears that he probably has at least a decent amount of "book-learning" about it.

He understands that it works, but nothing about it that we know of. The difference is huge. If he had decent "book-knowledge", he would know about the EM physics involved and such. What he has is a vague knowledge that it exists.

Well, we don't conclusively know that. The only wizard we've seen anywhere near high tech stuff is Harry, and we know he's not a fair representative for all magedom.

What I see is that it seems to be based on how the wizard regards technology. I suspect that if a wizard was your typical computer geek, then we'd see them having trouble with basically no electronics.

I'd disagree.  Butters has, in Dead Beat, given some thought to comparing magic to science, and created psuedo-theory about it.  Whether or not a Faraday Cage works is up to you, but I think it's an interesting idea, and Jim has certainly opened the door with Butters 'electro-magnetic-like field' thing to the fact that magic is in some way scientifically quantifiable.

The crack about a "Murphyonic field" struck me as more a Star Trek-ish joke than anything.