I can't listen to the vid on this computer but I spent a bit of time looking into this area.

The schools address is sometimes given as Dickenson, and sometimes as Dickinson (on the police audio it is called Dickerson). Why so much confusion about the street name of the biggest elementary street in the area?

Most maps show the street as dickenson but some show it as dickinson

I can tell you that the street sign in the google street view was a different one to the one on the day of the shooting, the google street view doesn't have the town emblem before the name (I couldn't make out if it was Dickinson or Dickenson on the streetview sign).

Both the old and new one have stop signs under them.

There is also another Dickinson Dr in Newtown

(EDIT: Sorry the link I gave was wrong, I'll try and find the right one)

I chased my tail for days with this issue and came up with nothing conclusive.

(EDIT: Now I can't find any dickinson dr in newtown, either my memory is fading or there is some shenanegans going on, but like I said ealier, I found nothing conclusive about the street names, just lots of confusion)