1. Overall, it's pretty safe in Australia. Just remain alert.
2. Yes, there are heaps of motels to choose from. Most of the hotels, especially in Gold Coast, provide secured carparks for their guests too. For the sector Brisbane and Gold Coast, may be you consider basing your accommodation in Gold Coast coz it's less than 2 hours to drive from Gold Coast to Brisbane.
3. I don't know about this.
4. The Australia Zoo (run by Steve Irwin's family) is a must, the Underwater World where you can dive with the sharks and seals, Sea World, Movie World, Dream World etc. A drive up Mount Tambourine is very nice (if you go there, do have lunch at the Polish Restaurant there).
You can climb the Story Bridge in Brisbane but perhaps the Sydney Harbour Bridge is more exciting.
Hot air balloon ride is a must. It's done very early in the morning when the air is still. The meeting time is usually around 4:30 am in summer and 5:30 am in autumn. They normally invite you to help inflate the balloon too. It's a bit expensive but definitely worth it.
As for Sydney, I'll leave it to the other Sydneysider members to recommend.
Oh, by the way, don't forget sunscreen, sun glasses and wide brim hats.
1. Australia Zoo - Glasshouse Mountain Tourist Drive, Beerwah.
Their website is www.australianzoo.com.au. Click "How to get there" and they have details showing you how to get there by courtesy bus, train, coach or self drive.
2. Underwater World - Parkyn Parade, Mooloolaba.
Website is www.underwaterworld.com.au
3. Sea World - Seaworld Drive, Main Beach, Gold Coast
Website is www.seaworld.com.au
4. Movie World - Pacific Motorway, Oxenford, Gold Coast
Please don't even think about it, it's so dangerous especially you'll be on the highway frequently. Although children over 12 months can use a seat belt (if a child restraint is not available), children will have more protection in a crash if they use child restraint that is suited to their weight and size.
It's not until a month ago that I still have problems with Devlin in his car seat. I had to sit in the back to keep him company (my poor hubby was like our chauffeur). I had his favourite toys and music ready. We did that for a year and then one day miraculously, he didn't cry when we put him in the car seat.
By the way, the police will carry out frequent RBT (random breath test) during the holiday season (I believe you'll be visiting during Easter?). The legal limit is 0.05.