I don't do it myself, but have a few friends in the hills district who commute by bus along the M2.
Most mornings its quick and hassle free, but it depends on how early or late you leave.
10 mins later can mean a 45 min longer journey.
The "pathetic" hwy from the freeway to Sydney is a complete joke.
M5 is always on the news.......
Its Sydney. Take it for what it is. You live in a city this big, its going to take time to get around in peak traffic times.
As far as rent goes - sorry but your budget won't get you anything anywhere safe. Just my opinion - Please don't shoot me if anyone disagree's.

Try a bit of a search for "granny flats" in the hills area. Some people on property's around dural etc have some huge flats they rent out on a cash payment basis.
Ask around it can't hurt.
Cheers
Brian