enclosure - you can pick up 45x45x60 / 60x45x60 Exo Terra glass vivs for around £50 - £60 if you keep an eye on eBay and the classifieds. A lot better than a mesh reptibreeze type.
If you go for a baby crestie you can keep it in a tub till it's bigger. That way you can set up a decent live planted viv ready for when it grows up.. have a look in habitat > planted for inspiration and a list of toxic plants.
Food - Repashy is one of the best CGD's. That or Clarks, I've used Komodo but they weren't that interested in it.
No need for supplements with the CGD and yes you can feed locusts. mine get CGD and locusts because crickets annoy me.
Lighting - they don't need lighting but UVB is beneficial and you also need to give them a day / night period rather than it just being darkish then dark.
Temps - yep, they need a heat gradient. Best way is a ceramic in a dome on the top of the viv