As tcasalert said....it's to drive your punters around on some of the scenics ie minibus licence allowing you to carry fare-paying passengers. Not sure what you guys in the east call it. It may sound like an unnecessary expense or inconvenience but as a casual pilot you will need all the work (flights) you can get. Also makes rostering less of a headache for the company. If you are dead against getting your F class then you may as well bypass Broome.
Sounds like you have a lot to learn Lasiorhinus if you think the only thing you do is fly up here.
If you have your first aid and night vfr work on getting some 210 time. Other handy aircraft time include 206 and perhaps 182 (depending on what company you are aiming at). Insurance companies are placing more pressure on operators in regards to minimum times/experience so the more time on type you have the quicker you will be released.
Depends on what you mean by turning up. Turning up for a day is unlikely to be successful. Staying in town for a while is probably more likely to score you work. If possible get to know the company pilots. The person doing the hiring usually turns to the pilots to see if they know or can recommend anyone. Most of all it's more luck than anything…just being in the right place at the right time.
AOC and aircraft register searches on the casa website can be handy. Otherwise don't be afraid to go through the yellowpages and ring operators themselves. A search on pprune should provide you with some info too.