I'd like to think it was older and had had its 1st meal, But anyway..
Yes you can use a fish tank, BUT, it is 2nd to the rubbermaid which is the norm and prefered or other brand plastic..
Never used coconut stuff, but spagnum is wonderful for babies, Our new hatch clean themselves up in spagnum but go to newspaper shortly there after..I'd suggest you stay with spagnum until it is a savage feeder..The daytime temps are fine & dandy, if there was a meal in him you'd prefer he did not see 75 though..Wee bit cool for digestion..Being a baby he is not acclimated/accustomed to the world as it will be yet..These guys will get tense and spring right out of your hand/s..Many/most will not bite but want to escape..Keep it in hand until it settles down, Do not grasp tightly but maintain a secure hold..He will in time go on to be a layed back pet if handled and loved..

Was this purchased from an OKC pet shop ? I sold a gravid female to a fellow who went on to hatch them and sold to such..