For MEL base you can typically expect to get 6 x 4 day trips per 56 day roster with usually a carry in trip beginning or end and/or some training. Trips are a mix of DXB and LAX. LAX currently signs on at 0825 and have a 38.10 slip, sign off 0805 4 days later. DXB is 2130 sign on and is a 41 hour slip sign off 2125 four days later. You have 18 days off per roster with the rest made up of A days where you are available if you owe hours for any reason. This is different from reserve, so your wont be on standby (although there is a provision for flying line holders to be given a standby duty - have not heard of it happening though) Transport in the form of taxis is provided to and from the airport for these trips due to them being long range sectors. There is a boundary for transport of course. There have been on occasion LHR trips, although these have not been seen for a while. In the past the LHR trips have been 7 days. On reserve you could be called out to cover SYD flying which might include HKG, DFW or DXB/LA trips. I'll leave it for so,even else to offer info about SYD flying.
In short, you can expect to work 24 to 28 days out of 56. There is a great mechanism for swapping trips including a private Facebook page for advertising trip swap requests and this is easily managed through CIS. From next roster there will also be a live open time system where crew can see availability of vacancy on upcoming trips and potentially offer to swap onto these. This of course will be dependant on operational resources.