Been googling and redditting and going through several apps to find the best deals but I figured the best way to find out is asked experienced travellers!

I read online its best to book 47 days before your planned DOMESTIC trip, I cant find anything for international however.

I need to fly from Sydney, Australia to Phoenix, Arizona in early to mid October (8th-17th) Im looking about. I have found a cheap flight today (February 23rd) to LAX for 400 bucks one way (this is for March 7th though). Anytime after April, it goes up, I have read on hopper that after April 15th flights will go up.

A flight to Phoenix costs 700 bucks, an extra 300 dollars from LA to Phoenix?! I can find a flight for 60 bucks from LA. I looked on the ITA matrix software and yesterday prices to Phoenix was 699, today it was 703…. So I guess I have several questions:

How far out should I buy a ticket?
Would it be best to book separate flights if the price is that different?
A. The only thing that worries me is having to get my luggage and re go through security and timing my flights correctly so I dont miss the second flight Any advice is greatly appreciated guys!