The govt has stated many times that it will not alter the PBS as part of the FTA. Also I think the effects on Australian culture have been heavily exagerated, but either way they probably had the effect of convincing the Aust negotiators not to trade away Australian culture*.
The idea of free trade is that it is mutually beneficial. There tend to be initial losses in employment in both countries as inefficient industries lose market share to foreign firms (this will occur from both sides). But employment would then pick up in the long run. That's the theory, it's not 100% right, but it's a pretty good guide.
The basic effects on the economy (to use a simple example) is greater access to US markets for Australian farmers and greater access for US manufacturers to Australian markets. Farmers will benefit because they will receive higher prices for their produce (due to lower tariffs - taxes - on exports) and pay less on their equipment (lower tariffs on imports).
So what? Take with one hand and take with the other? What's the point if it just results in more unemployment? Well the theory goes that free trade will help in producing a more efficient allocation of resources, it's called comparitive advantage. This should ultimately create more employment and higher incomes. But it will create hardship for some in the short term.
As for the argument that this will probably be just a "free-er trade" not an actual free trade agreement, that is 100% true. All I can say is that it is part and parcel of politics.
* About Australian culture: if the recent local comedy movies (minus a few notable exceptions) are a sign of Australian culture then bring in the demolishers! I'm getting rid of Australian culture as fast as I can!
