The 2nd noise could be rats or mice.
Possum or rat in roof.
Rats either way if you think there may be possums in the roof then every effort must be made to get them out before you try and deal with rats.
Urine may also seep through and damage your ceiling.
If they are nesting on the insulation in the roof this can become damaged through constant urination and will require replacing.
Possums will only be on your roof regularly for three reasons they are living in your roof they are living on your roof or they are using your roof to get from a to b.
The subsequent liquid release will leave a mark as well as a pungent odour.
A possum is a large animal and it has no qualms relieving itself in your roof.
Their droppings tend to be scattered everywhere within a roof whereas possum droppings are usually found in small clusters often around their chosen sleeping place.
Possums and rats can cause damage in the roof by eating through electrical wires.
Possums do nest in roofs but are mainly active at night and although they are agile climbers are heavier than rats in their movements.
They normally scurry around both day and night.
Other tell tale signs that a possum is living in your roof can be stains on a ceiling or drip marks down your walls caused by urine.
They can be extremely noisy running and thumping through your ceiling.
I have seen possums eating ratsack and seen one that had a rat trap on it s leg and if you think they are noisy running through the roof you should hear them when a rat trap is attached to their foot.
They may eat fruit and other human leftovers but tend to feed on native vegetation and are not found as often as rats are scavenging indoors and or ransacking stored foodstuffs.