cheezz, I have the hard-copy NY Times article and the baker's recipe never goes over 450
The pan/lid is preheated in the oven 30 minutes PRIOR to the end of the last 2 hour rising, then the dough is added, the lid put on, it's baked 30 minutes, lid comes off and it's baked another "15-30 minutes" (again, from the hard-copy recipe).
I think the confusion is coming from the video because the baker mentions getting the pan as hot as possible and he says "500". But I don't really think it matters that much. From everything I've read and all the variations of temperatures, it still works.
Thermometer: The Baker never mentions an internal temperature (video or article). I'm just going to use it because it helped with my French bread. Although my crust is crunchy, it didn't "sing, the term used when french bread crackles fresh out of the oven.
I made French bread twice. The first time it didn't sing. The second time I put in a probe and left it bake until internal temperature reached 200 degrees. It sang for 5 minutes that time.
I have a Poldar probe thermometer (thanks forever, Pat!). It's connected by a metal-covered wire to a digital read-out display programmed to ding whenever the probe reaches your temperature. "Instant read" thermometers would also work.
I wouldn't bother buying one just for this though...he seems to have his times down pat.