I will look into a better light. I think $350 USD (approx $500AUD) is a large chunk for a single piece. I hear what you are saying though. The things I feel I cannot skimp on are the light and filter/extraction. Will see if I can find a light + filter/fan for approx $500, as I think it makes it more economical for me. What would be your next step down from the hlg 260w? Any preferred brands for carbon filters? The internet is swarming with BS about what actual brands are good, people plugging brands for kick back etc. So asking the growers here gives me the biggest confidence in the suggestions.
If you are up for a bit of DIY wiring, standard LED bulbs can grow some very nice weed for something like 1/2 the price of commercial lights. The difference may even be bigger down there after duties and the like are factored in.
I would definitely go for a 2x4 tent rather than a 2x2, especially as you intend to help family and friends. You would be able to play around more for strains for different purposes with the extra space. Also, height is your friend. Don't buy a short tent. I would not go less than 6 feet myself, and the diy I built is over seven.
Re. stealth, you really need to be on top of the smell issue. I would go with 6" if I were you, and choose a carbon filter that has been well reviewed by experienced growers. Once you discover a smell problem, you may already be too late, and it will be a bugger to fix quickly. Don't even think of trying a grow outside on your property. Even strains with reputations for low smell are not no smell, and they regularly turn out to be different than reputation suggests (my current Northern Lights is high on the stealth list, but was way too smelly to not notice outdoors).
And one other thing given the consequences of your being found out. Tell no one, no one, that you are growing. If you can't keep your gob shut, do you really think others will be able to? If you supply some to friends, just tell them that you have some that a friend gave to you on promise of not saying anything. Even here in Canada where what I am growing is perfectly legal, I am very careful about who knows what I am up to. The issue for you is not just the local law however serious that risk is, it is also the local teenage stoners who will steal your stuff and be happily waiting for the next grow. Once the word is out in the wrong crowd, you could be buggered permanently, law or no.
Good luck with your grow mate.