clckn2000, glad you like yer new bike.
Firstly, it's unlikely that you will completely stop the front brake from squeaking.
After a bit of detective work on mine, i found out that it's the suspension forks that resonate. This is probably due to the fact that they're not the best quality.
I did change the pads to Jagwire ones which were a little better, but didn't cure it completely. Slightly less binding on the rim!
They now only squeak for the last second before the wheel stops completely.
As for the battery, it's probably unlikely that you will be able to buy a direct replacement.
Depending on your skills, you could either buy a rear rack mounted aluminium cased battery, from the likes of Goldenmotor. Then connect the battery's output to the controller with some suitably rated cable.
Or integrate a LiFePO4 battery (Ping) into a suitable container with connections for charging and to the controller. Also a switch to cut battery power to the controller whilst charging. Possibly an inline fuse too. Other more experienced members can help you with this.
The former would be the easiest, as the battery packs already have a charging port, fuse, BMS and battery on/off key switch built into the casing.
As for the rear hub motor, it has a male/female connector which allows the whole wheel to be removed. I haven't checked, but i assume that it can be replaced with a standard 24v rear hub wheel.
Again, the more experienced members can give you guidance if you ever need to do this.
Most of the other components are standard fare and any good bike shop will be able to help you out with fixing or sourcing parts.
Hope this helps