I will need to do more exploring in the next few weekends, the house is full of K&T and I wasn't really ready to dig into the electrical while visiting. EV, I think you're right about the 30's on the lower side though, they look like 2 separate circuts.... maybe they forgot the "tie-bar" (insert, "Nail") for the cb's and the water heater gets tied together somewhere else on that circut. On the boxes above you mentioned, it looks like K&T leaving the boxes and the old ungrounded romex going to the panel.
Sorry about the bad pic's, I'm new to the phone camera thing [Linked Image]
Regards,
Jerry