Reading up more on the DS18B20 it looks like it needs to be queried to report a temp, which is great for power saving when connected locally... but if I as a total n00b understand this then I would need a transmitter and receiver on each end to close the loop.
That's correct, you would need a microcontroller on each end, on that queries the DS18B20 and sends the data and another one that receives and display the data.
So I'll go do some more googling but if I understand this at all if it is at all possible to only use one Arduino I'll need a digital temp sensor that skips that greenie power saving stuff and reports a temp on power up, or every few seconds or something. Am I way out in left field with this thinking? If I can keep the remote transmitters to only run on smallish battery and last a while that would be nice.
I haven't seen any ready-made temp sensors that sends wireless data that can be received by some standard receiver module but that doesn't mean that they don't exist.
I would have built my sensor/transmitter around a standalone ATmega328p running straight from a few AA batteries. The 328p is not expensive and it has some nice power saving modes that consumes very little power. The same is not true for a full blown Arduino since there are other components onboard that consumes power even when the 328 is powered down.
The transmitting microcontroller would be powered down most of the time and you only have to take it out of sleep mode as often as you want to query the sensor and send data so the batteries would last a while.
But building something like that would require soldering and maybe also flashing the bootloader on the new ATmega chip so it might not be ideal as a beginners project.