You should take these questions over to DIYaudio where you'll run into a lot of builders. :)
The wiring should be UL1015 listed
That's really specific and unnecessary. UL1015 is 600V PVC shielded appliance wiring material. It's in an enclosure, there is often no need for shielding at all, and it would be detrimental to the build in many locations. Where shielding is required, there are any number of UL style wires that would be suitable depending on where used, how supported, etc.
@greg7 - I have designed and tested many DIY cables and the following are the wires I have found to excel when used for the signal/live wires in all my cables
One of the things that can hinder the performance of wire is the insulation
Neotech UP-OCC copper with Teflon insulation (Dk=2.2) is an extremely good wire
VH Audio UP-OCC copper with AirLok insulation (Dk=1.45), is also extremely good, but for some reason I preferred the Neotech, while others preferred VH Audio
VH Audio also has a UP-OCC solid silver wire with AirLok insulation (Dk=1.45) that is about as good as you can get
Solid wire is better than a stranded wire
I avoid the use of silver or gold plated wire for the signal wires - plating seems to impacts sound quality
Mundorf has a Silver with 1% gold wire that lots of people like
As a previous posts above mentioned, the best insulation solution is to use Bare wire in a slightly larger Teflon tube (Dk is very close to 1.1) ,
WRT the neutral wires in my cables - I use a stranded silver plated copper Mil-Spec in Teflon wire
So does using premium wire really make a difference?
Regards - Steve