Confused re min max cooling capacity

The units are quite similar in capacity, both being rated at 16kW. The minimum to maximum range is the minimum the unit can run down to before it has to start cycling on and off, up to the maximum heat transfer it can achieve.

One reason the maximum is different to the rated value is that the manufacturers are working to meet environmental ratings. Basically, the higher the operating point, the less efficient the unit becomes, and so they rate it at lower than peak capacity so they can meet the required efficiency standards at the given price point. Also some models won't run continuously at higher than the rated capacity, and is only available as a short term boost.

For the minimum power, lower is better, and the Fujitsu has a wider operating range than this Mitsubishi. This helps the unit run more efficiently when less cooling power is required. However, you will still probably be limited by the minimum speed of the indoor fan, as on most units this doesn't vary all that much, and restricts how few outlets you can have on at once, and also adds a constant power usage regardless of the amount of cooling. About the only units that will offer a highly variable internal fan are from Actron.

I doubt that the first system just limits you to the open plan area. It's more likely to be something like on a 45 degree day you may need to turn the other zones off and close off some doors too keep the living area at 21 degrees. On less that the hottest days, you should still be able cool large areas of the house, and bear in mind that the less you keep conditioned, the less energy you'll use doing it.

I don't think you'll be short on capacity. Our current house has about 130m2 of conditioned living space (3 bedrooms + lounge + open plan). It has a 12.5kW Toshiba ducted unit (3.3kW min - 14.1kW max), which seems to have more than enough capacity to keep it all cool on hot days. Being Adelaide, it should be a similar climate to Perth. We don't have north-west windows, but if they are such a big load then you may be better to get some external shading on them as well. Then on the hottest of the hot days it can make sense to close off some of the house and just cool a smaller area.

You won't be wanting to run it above the rated capacity much anyhow, as it operates less efficiently there, so I wouldn't see capacity as a reason to favour the Mitsubishi over the Fujitsu. If anything, I'd look at that 9kW minimum of the Mitsubishi and think that might be too much power for your 95m2 on less extreme days, and so it'd be cycling in and out more and probably less efficient.

Other things to watch are the quality of the install - the better installers can probably get better airflows through the ducts and so have more efficient and quiet operation.

The duct insulation is also something to watch for, as if the ducts are poorly insulated, then you get heat gain from the roof space. For a dark-coloured roof and minimally insulated ducts you can lose a couple of kW of your cooling to the heat entering the ducts. R1.5 ducts seem about the right balance between efficiency and bulk.