It doesn't matter what technology of panel you choose, as the important factor is buying from a quality manufacturing brand that has a history, track record, and good warranty protections.
Both monocrystalline and polycrystalline ("multicrystalline") panels work well in Australian conditions.
Manufacturers focus on providing budget products, standard products, and premium products. Avoid no-name panels as you really don't know what you're buying.
A string inverter is a single inverter, typically it is installed on a wall which all panels are connected too. It's important to never mount a string inverter in full sun, as direct sunlight kills inverters.
A micro-inverter is fastened to the back of each individual solar panel so each panel operates independently with microinverters, and overall your solar system will produce more energy.
Inverters are the part most likely to fail, as they work hard all day converting DC electricity to AC.
We recommend "oversizing" your inverter with additional solar panels to a maximum of 33% above the inverters rated power capacity (kW). You'll directly benefit financially with a larger solar subsidy and you'll produce more energy during winters, mornings, and evenings.
Oversizing ensures you get the best value for money because during the winter months when there isn't a lot of sunshine your inverter will get greater use and you'll be paying back your investment faster. Sometimes you're also restricted by local electricity distribution network regulations, so "oversizing" is an easy way to install a larger solar energy system on your home.