Yes you can. Qantas and BA are part of the OneWorld alliance and reciprocate on their frequent flier programs.
No, these airlines are not affiliated.
You can qualify for Qantas frequent flyer points by purchasing services from Qantas partners such as Airlines, Credit Card companies and more. You can get more information at the Qantas website.
The Qantas Frequent Flyer program is a wonderful program that allows you to earn points through such events as using credit cards and car rentals. One can redeem these points for many different products at the Qantas online store.
A trans-pacific flight such as this (round trip) is usually available for about 100K frequent flier miles. If you go out of season it maybe possible to go for less. Business class would usually cost more.
There are many benefits of being a frequent flyer. You can collect points and discounts for your next flight, you may get priority boarding and you may also have rights to an airport lounge.
The simple answer is yes. QANTAS are part of the One World alliance. So you would use the QANTAS miles but you would be flying on British Airways metal. They have flights from Philadelphia to London Heathrow and then to Rome.
You don't mention which city you're flying from, but Sydney to Mackay will use up 12000 points (one-way) or 21700 points with taxes (one-way).
You will earn points with each flight you make on American Airlines. You can then redeem the points for flights or for upgrades on flights.
It is unknown and is not the sort of information that airlines release as the information would be valuable to a competitor.
The answer to the question about the credit card company provides frequent flyer points is that this information can be obtained with the concerned department of the company.
It needs a minimum of 250,000 frequent flyer miles
For someone who is a frequent flyer, a frequent flyer program allows the customer to earn miles or points that one can exchange for another plane ticket, purchasing hotel rooms, renting cars or general shopping.
The discount one will receive from being a frequent flyer aboard US Airways will depend on the number of miles one has undertaken. Usually, however one will use their frequent flyer points towards free flights.