As of last year, you could work offline for two weeks at a time, but I think they've changed it. It'll take some digging to find the answer, but there's an option to set how many days to cache for Offline mode, and I set it to 99 and it seems to work??
You can export Iges, SAT, STEP, SMT, and Fusion 360 f3d files.
You can also export drawings as .dwg files.
There are a LOT of people using Fusion 360. The CAM is supposed to be pretty good, as it's based on HSM Works. Development is constant, with lots of updates and features added all the time. Some things still have a ways to go, but it's a really powerful package, that most people can use for free.
Personally, I don't think it will remain free forever, but $25/month (if paid annually) is still a pretty good deal. A fraction of what most people pay for their cell phones.