You could get an AC tech to come out and take a look, but you'll have to pay them. Otherwise, you'll need to get up into the ceiling and have a look. Check that none of the ducts have come loose from any sockets, that there are no rips or missing insulation. Ideally the ductwork should look shiny and not deteriorated. 8 years shouldn't be long enough for it to wear out too much. Have a look at where all the outlets are. Is there one in each room? You want to make sure the system has been designed properly in the first place. Try and find the model number written on the outdoor unit, and look up the kilowatt rating online. As a rough guide, the system should be sized to at least 100 Watts per square metre floor area in the house. So a 200sqm house would need 20kW (rule-of-thumb estimate, there are many other factors). Look for the return air grille (usually egg-crate style). It will probably be located in a hallway or similar area. These tend to collect dust on the ceiling side where they draw air back up into the system. If the house is for sale it might have been cleaned. You should be able to open it up and have a look at the filter. This will give you some idea of how frequently the AC has been serviced (if at all). Lastly you could turn the system on and see how noisy it is. Very noisy fans may indicate that bearings are wearing out and might need to be replaced. Fortunately Daikin are a mainstream brand, there's lots of companies that can service them and should be able to get parts if need be. An 8-year-old system should be readily serviceable, but I guess you're hoping to avoid a breakdown as soon as you buy the house. Heating & cooling is usually the biggest energy expense in a house (hot water is second place) so if you can get the last year's worth of power bills you can have a look if the running cost is reasonable. Overly-high running costs would indicate either a design problem with the system (not set up correctly) or with the house (inadequate insulation or shading) or a mechanical fault in the AC. No point having an AC system that you can't afford to run. Hope that helps!

Cast a block of concrete, make up a frame to size of base you need, you could tint it if you like, this would be a fast and easy alternative to raise it to the height required add the appropriate holes for the pump and electrical requirements before the concrete sets, have seen this done and it works a treat.

Those seem to be trademark varieties from outside Australia. You could contact Daly’s fruit or Diggers Club to see what dwarf varieties there are available in your area.

Have you been into the closest timber supplier? Often they won’t have stock on their website, you have to go in and ask.