1. I might have an extra Opal card which I can pass to you. It is free to get the Opal card, you just need to topup AUD10 i think.
2. There is a YHA at the Rocks which has quite good reviews but i think it is more expensive than your RM80/night
3. It would be expensive to rent a car if you are solo since you dont have anyone to share with plus parking in Sydney is not cheap

Sydney is quite doable with public transport if you dont mind walking. There is a free bus which goes around the main street, George St with stops at Circular Quay, Martin Place, etc.
You can do the Congee Walk from Bondi which is accessible by train (Bondi Junction) and bus or direct bus from the city. If you are there between Oct 22 to Nov 8, there would be Sculpture by the Sea throughout the walk which you can visit also.
You can try to train the ferry to Manly from Circular Quay for an another experience plus views of the Harbour Bridge & Opera House. Another free activity is walk across the Harbour Bridge starting from the Rocks District or Milsons Point. While at the Rocks, do visit their Foodies Market which is on every Friday and Flea Market on Saturday and Sunday.

Hope this help.

1. I will have to go back and look for it. It still have some credit left. You are also going to Melbourne right, do u need the myki card? If not mistaken, that you have to pay but I got it free from a friend which I can pass it on to you.

It would be too rush to do congee walk, manly and Watson Bay in one day for me personally cause I dont like to fit too many things in a day. I think you can skip Manly since you already going to do the Congee Walk as you will be passing by plenty of beautiful beaches along the way such as Bronte, Bondi, Tamarama, Congee, etc. I actually have not been to Watson Bay myself so cant advise much on the fish and chips You can always do Congee walk early in the morning cause that time it would be end of Spring so you will get longer day. Just make sure you keep yourself hydrated and stops for food along the way.

Either side is fine mate, you will find the plane actually turns around to head towards Kingsford Smith Airport so you can get a good view of the beaches and the city either size. Just make sure you get a window seat. Also most Malaysia flights arrive early morning and the sun can be quite bright, wear shades!

Cheers,
AK

visiting sydney and tazmania nxt week.

was thinking if there's anything visitors prepaid sim card which can be purchase before i go there ?

Can you share more on how this 2AUD prepaid sim work? Is there a minimum amount? Say I will be staying in Australia for 7 days, do I pay only 7x2=AUD14? Thank you.