You'll get different answers from different people, but don't be too confused; most of it will work and there are just different options. I personally think ceramics are garbage which have alternatives which are superior in every way, but others like them for some reason... probably because of commercial influence. I'd personally just use floor heat (personally I go for heat cords but for people only keeping small numbers of snakes mats can be more convenient). By putting the floor heat under only part of the enclosure it's very easy to provide a thermal gradient. The exact temperatures aren't too important but a cool end from the low to mid 20s to a hot end of low to mid 30s will be fine.
As others said, don't worry about lighting unless you want soft lighting for your own viewing pleasure.
Darwins aren't really basking reptiles so I wouldn't use a heat lamp. They're nocturnal, naturally active in the evening when the ground is warm, so floor heat is best for them. If you're in a cold climate you might want something to keep the air warmer. Being in a fairly warm herp room is plenty, but if you only have one snake and it's in a cold room you may want to look at heat panels (my personal option would be a home made heat panel made from a heat cord). Years ago I'd have used blue globes and these still work, but are now basically obsolete.
Substrate is a matter of personal preference. I use paper towel for hatchlings and most people prefer some sort of paper such as newspaper. For adults there are countless options. Newspaper or Breeders Choice work well, there are some more expensive commercial options if you like splashing more money around gratuitously. Avoid sand, and I'd personally avoid cocopeat as it's messy and while it's probably harmless the snake will end up eating it when it gets stuck to their feed.
Good luck and keep us all posted!