The biggest factor in most of the questions you asked will be where exactly you are going. The further north you go, the more nasties you get in general (but the nicer the country gets to make up for it :wink: ) I've been an avid camper for atleast 5 years (not much but i'm only 20), and the nastiest thing i've seen was a King Brown Snake in my backyard, not even when camping. Also had a red belly black snake in our laundry
. In each case they were more scared of us than we where of them. But all snakes should be left alone, and can get very nasty if their threatened/cornered.
Spiders arent that bad, just dont stick your fingers where they dont belong, if you want to lift a piece of bark or sumthing to see whats under it, us a stick. Simple common sense usually works a treat. Contrary to popular belief, funnel webs dont jump, and can't climb... so dont sleep on the ground without a tent, and make sure u zip it up.
If bitten by a snake, your supposed to wrap the limb up above the bite tightly to slow the blood flow, and therefore slow the spread of the venom. But it would be best to find out from someone who knows what they're doing exactly, maybe do a basic 1st aid course before you come, I think treating snake wounds is pretty generic regardless of the snake, just with some you have to act quicker.
Mozzies are reall bad in summer, and all year round in the northern states. Flies are just as bad if not worse, personally, i'd be more scared of stuff in the ocean than on land (blue ring octopus, box jellyfish), but again, theres not really many reports of people dying from poisonus critters. Never been there, but I hear crocs are scary up north. And dingos in some places, but they're usually ok as they're scragly little things, but could easily take a child (always watch ur kids when ur in teh bush)
Dropbears are probly the most ferocious critter you'll find in the bush, try not to camp under gum trees, and spray the perimiter of the site with a good dropbear repellant (just ask for it at the camping store :wink: )
Oh, and if your swimming/snorkelling, and you see a sting ray/sand ray, dont go near it, and especially dont step on it like I once did (they dont like it :wink: ) - their tail has a poisonus barb and hurts like hell