Gross meter = all your solar goes into the grid (in an administrative sense) and is paid at whatever FIT rate you receive. All power you use within the house is then drawn from the grid (in an administrative sense) and charged at the (higher) price for grid power.
Net meter = your solar is connected to the load side of the meter so the meter only "sees" the net flow into or out of your home to the grid. So if you are generating 3kW and using 2kW yourself, then the meter sees that as 1kW going into the grid and that's what it records (it has no idea how much is actually being generated and used, just what the net flow is). So if your FIT is lower than what you are paying for power this will result in lower bills.
Note that net metering is on an instantaneous basis and is not based on accumulation over time. So if you generate 3kW right now and use 2kW then you receive the FIT for the 1kW going into the grid. If you then turn the oven on and the sun stops shining, so that you are now generating 1kW and using 4kW, the 3kW being drawn from the grid will be charged at the applicable rate. The power you previously exported is not "banked" or stored - you sold it and were paid at the FIT rate, now you're buying and will be charged at the appropriate (higher) price. It's all done on an instantaneous real time basis with nothing "banked" or "stored".
So if you want to remain on grid and minimise your bills then the standard answer is to shift your power use to when the sun is shining. So instead of running the dishwasher at 10pm and paying for power from the grid, you run it at noon and use your own power that would otherwise be exported at the FIT rate.
One way to maximise use of your own power, if you have electric storage (with a tank) hot water is a device such as the Immersun or Optimmersion. This is an electronic device that monitors power flow into / out of your house and adjusts (in a constantly variable manner - like an audio volume control but fully automatic) how much power goes into the water heater. So if you are producing 2kW from solar and using 1.2 kW for your appliances at that time, then the Immersun sends the other 0.8 kW into the hot water (up to the point where the tank is fully heated and the thermostat switches it off, after which any surplus power is exported to the grid in the normal manner).
If you've already got solar panels and electric hot water then in practice this device turns your existing water heater into a solar one, albeit an electrically powered solar heater but it's still making use of the power you generate yourself so as to minimise both import and export to the grid. So you use the power that's worth 5 cents / kWh (FIT) instead of paying whatever rate to buy power from the grid and heat water with it. The device is able to incorporate a "fully heat the tank using grid power overnight if it wasn't fully heated once the sun went down" function so that you'll still have hot water even if there's heavy cloud all day or you have the air-con running and using all your solar production.
To use the Immersun all you need is an existing solar power system and an electric water heater of sufficient capacity to provide hot water with once per day heating (same as normal off-peak except for the different time of heating it).
Note that this works with conventional electric systems only and cannot be used with heat pumps.
Any electrician could install it, but you'd be wise to find a good one since most will have no prior experience with this as it's a relatively new product that doesn't (yet) have a lot of market penetration.
Retailers - no comment there since I could reasonably be considered as biased toward Momentum (100% owned by Hydro Tas).
http://www.momentumenergy.com.au/
I'll add a comment though that despite the rather large problems Hydro has at the moment, Momentum customers in the mainland states won't be facing power shortages or having their lights go out. So long as Hydro can't generate that power (and has no means of getting it across Bass Strait with the broken cable), supply is simply being purchased from the market (ie rival generation businesses) with Momentum acting purely as a retailer. So it's business as usual so far as Momentum and its customers in NSW, Vic and SA are concerned.
Big thing to look out for with any retailer is "discounts" and other complex pricing arrangements intended to confuse rather than inform. Just because you're supposedly getting a 30% discount from a retailer doesn't mean you're necessarily paying a lower price than with another retailer that offers no discount at all. Getting 30% off isn't a good deal if their prices were double what others were charging to start with. So you need to look at the actual prices and ignore the "discount" scam.
Time of use pricing, where it's an option, is another potential trap. Some will win, some will lose, and it all depends on how much you use and when. My personal opinion is that you've best to avoid it where possible unless you're very sure you'll actually save money due to most of your use being at the cheaper times.