i found an exotic store that carries em.ill be picking up a sling tomorrow.they said they are a lil bit bigger than a quarter.i have a 5.5 gallon.i was gonna let it sit normally long ways since its small right now.should i put it sideways or as is?ive read they are semi arboreal.or should i just keep it in a deli cup til it gets bigger?

ive read about their natural habitats and from that i was gonna mix some peat moss or eco earth with sand.im gonna put in some tree root looking branches on one side so it has opportunities to web a retreat under the "root" and above the "root",a longer three armed branch to sit in the background across the back of viv and some deep enough substrate in case it wants to burrow.i was also going to put in a couple of flat rocks stacked with some smaller rocks around it on kind of a sloped sub to mimic nature.sound good?
my room temp sits anywhere between 79 and 84f.i read temps for them should be between 75 and 80f.would i have a problem or would it be perfect?
im reading mixed things on humidity,some say 60-70 and some say they like it dry.where they come from its arid so dry?like 30-50%,only humidity causing is the waterdish?
i keep scorpions and have experience with the fast, venomous arachnids but ts are new to me and im ready for this beautiful aggressive punk.
oh and when i go id rather have a female because i read they get bigger and live longer.is that true?i wouldnt be able to determine gender til its adult,right?

any and all suggestions,comments and info welcome.thanks in advance.