in the most basic set ups 1 hide is all thats needed.
the gecko will choose its hide if there is more that 1 based on comfort
and where ever its most comfortable its less stressed and happy.

same or different hides? doesnt matter imo
if it chooses one hide over another could be based on the hide itself
or environmental conditions / needs

a 10 gallon is perfect for 1 adult leo
hide box, water bowl, food bowl and paper towel as a substrate
small compact easy to maintain
if you want to do the vivarium thing a 20L would be ok too and there is room for expansion

a uth will raise the temps aprox 10 degrees above ambient
if needed a heat lamp can help maintain proper temps
keep away from drafts and direct sunlight

males do get bigger that females
not so much that it really matters though

Kirk