PVC is made to be run underground. If you leave it above ground you should paint it so UV does not make it brittle.
You need unions for the pump. Check if your filter should comes with unions.
You just have SKIMMER -> DIVERTER VALVE -> PUMP -> FILTER -> DIVERTER VALVE -> RETURNS ?
yes that sounds right. so ill put one under the skimmer and one just b4 the return to pool, yes?
im not sure if this pool has one or two returns. any idea on this? bc that would change the valve i need for the return i think?