I think you meant concrete pad not cement. A 6 in pad should work for you.
4 To 6 inches
should be at lest 4 inches
any project i do it 2x6 walls all around then 2x4 interior walls. Matt O&P Concrete
It should have about 4" of base, compacted and a 4" slab of crete on top.
the concrete should be 6" according to this site http://www.de-fontenay.com/poolcon4.htm
Thick is an adjective not a noun
two and a quarter inches is desired for driveway for most domestic vehicles
It is very thick. At ground level and at 20 deg C, Venus's atmosphere is around 50 times as dense as the Earth's.
cot mattresses should be around 10 cm thick
It depends on how thick you want the concrete.
I have a in ground pool. I fight a mold that is white and thick in the pipes. Sometimes it is slimy. My water tests are just around nomal.