I wouldn't worry too much about snakes,especially in more suburban areas.
Some people have lived here for years and never seen one.
They are often seen where a lot of building is going on,perhaps they have had their habitat disturbed.
We live semi rural and have seen them - to the extent of having one in the house

Roos are not a problem either,you are not likely to see them in suburban areas.
They will defend themselves if threatened but that is normally a worry if you have dogs.
We had a Koala in the trees at the back a couple of days ago,we had to keep the dogs away from the area.Koala's do have huge claws for climbing trees but will swipe a dog in defence if pushed.
Ants and small creepy crawly s are a pain though.It can be a constant battle to keep ants out of the house.