Here is a thread I authored for cab wiring:
http://www.wfmachines.com/forums/showthread.php/37241-Cab-and-Auxilliary-Wiring-for-a-4X5
The tractor was a 455. but as far as the cab wiring, it should be near identical to your 445, if not identical. My cab was a Femco, so there will be some differences. If you're going to add a radio, you'll need two additional power feeds. One that is full time battery (to power the memory and clock circuits) and the other from the output of the accessory relay, that is added as set forth in the above link. Be sure to add fuse protection for both, as close as possible to the source. Many of the aftermarket radios place their fuseholders directly behind the radio. This does nothing to protect the wiring between the source and the radio. You sure wouldn't want your tractor and cab to burn up from un-fused wiring that is damaged and shorted to ground.
I restored the Femco cab in the above link. Once I had the cab disassembled and the replacement components fabricated, I took the components to a local sandblast & powder coating shop. They sandblasted the cab components and powder coated them in JD green. They also did the mounts and powder coated them in gloss black. All for $350. It looks great and the powder coat is durable. I don't think you could fool around with other methods for that kind of money, durability, and appearance.
Do you have the service manual and wiring diagram for your 445? If not, you can download a copy here:
http://www.mytractorforum.com/334-john-deere/142324-john-deere-425-445-455-technical-manual.html
You'll need to pay attention to what electrical items you're adding. The stator circuit (charging circuit) of the 445 Kawasaki engine has a 15 amp maximum output. Your heater blower motor will consume most of that. You'll want to add up the current ratings of all the devices you're adding as well as those that are OEM. The total shouldn't exceed 13 amps, you need a cushion for the current to charge the battery.