As said before, if its on one ticket, then your bags will be checked through, even with the long layover in KUL
. In KUL
you will even remain in transit and in case you want to visit the city (although it's quite a long trip) you will need to enter KUL
. Your bags will however remain in transit and later you just come back, pass security, pass passport exit control and all that. You don't need to advise anyone about that, you just do it (and make sure you meet the malaysian immigration requirements if you plan to exit the airport).
A side note: Be aware of the distance from the airport to your hotel, i.e. a ride from HKT
to Patong or Karon will take an hour at least! Not sure if you're on a budget, but if you are you might use the local shared minivan services offered from the airport to all the hotels all over the islands. They're dirt cheap (you pay at a counter in arrivals and get a voucher you give to the driver) but will make a stop on the way in a local travel agency and they will try to sell you hotels and excursions. It's not cool but if you say you have all you got you will be fine and the wait is worth the cheap price. Be aware that if yourr flight back from HKT
to Australia is too early, then you want be able to use the minivan service on the way back to the airport, since they usually start at 7 am or so.
If you prefer to take a taxi, keep in mind that most taxis in Phuket have no meter and they will try to rip tourists off. However, at the airport (you exit and go right), there is a little hidden hut with a big sign "Taxi Meter" on it. There you get a metered taxi and fares are published on a board. You will not be ripped off. On the way back of the airport (unless you use a minivan serivce as described earlier) you will have huge troubles finding a metered taxi though. In my case my flight was very early and I could not use the minivan services. The cheapest thing for me was to arrange the way back from the hotel to airport directly through the hotel. It was more expensive than the minivan service, but way cheaper that what all the taxi driver wanted (and it was more reliable and prepaid).
If you want further information you will find a lot on google or just let me know.