1. Yeah, try out for 4 schools. Definitely recommended. Don't think order of preference matters too much tbh. Yeah, SGHS, NSG, St George, Hurlstone sounds like a good list but you may want to add in a partial selective (e.g. Macquarie Fields, Sefton) instead of a 4th fully selective school if you're in a comprehensive at the moment. But it's your choice.
2. Academic performance - Years 7 to half-yearly Year 9 performances are quite irrelevant to your application. What truly matters are: your Year 9 yearly AND most importantly, your Year 10-half yearly. Your Year 9 yearly performance sounds great so hopefully, you replicate the same/better standard in your Year 10 half yearly report.
3. NAPLAN results - If it's all in the top bands for the Year 9 one - it's definitely a gr8 thing.
4. Extra stuff will you the edge against those who are academically similar to you when they try to distinguish who is worthy of a placement and you have a great amount of extra-cirriculars it seems.
5. Well, from my own experience, in Year 10 ..I got 3As 5Bs for Year 9 yearly and 6As 2Bs for Year 10 half-yearly, my yr 9 NAPLAN was like 3 arrow band 10s, 1 mid band 10 and 1 mid band 9 for READING LOOOL and I got offers from Syd Tech (chose tech) + Hurlstone. If there's one thing I regret not doing is probably trying for 1 or 2 more HIGHER schools like Fort Street or something but doesn't matter too much in the end tbh. However, Hurlstone is a heavy advocate of the entrance test... They base probably 90% of your application/entry into the school on it (well when I applied for the school, it was like that), where I had friends with MEDIOCRE reports (no As) making it in while some friends with better reports failed to get in.
6. Just go in fresh. Have a good night sleep if you have an entrance test + interview for a school. Go for it. It's your last chance so make it good (don't have any regrets).
7. IMHO, a person of your calibre should get into St George or Hurlstone at least but no guarantees. Don't get too confident but yeah, hopefully you'll end up in 1 of your applied schools! GL!