I have always wanted to visit Australia. Do you know any good travel advice if I should go?
Well its the biggest country in Oceania and the world's sixth-largest country by total area. SO youll have plenty of spots to visit, May I recommend visiting Sydney first. 
That sounds great! What kind of wildlife would I expect to find?
Around Australia's capital in Canberra you can find lots of Kangaroos and a huge zoo there, and you can even find kangaroos in urban areas in Sydney, Thats why I recommend you go there first. 
Is Sydney a heavily populated area? I wouldn't want to be sitting in traffic everywhere I go
Well As of June 2016 Sydney's population was around 5,029,768, So its pretty crowded, But I'm sure youll get along with the locals, Australia has very friendly people. 
Is the food good there?
Yes just be sure to ask one of the residents of the city which restaurants are the best and be sure to call the locals "Sydneysiders". They seems to respect you more for it.