Hi Paul, Perhaps you already know, Ficus Macrophylla is the Moreton Bay Fig. As such, yes, they do like the sun, but knowing the Sydney winters ( I moved from Sydney, after living there for ten years, to Qld three years ago) it may be advisable to give it some protection from frost etc. I used to keep my 'frost sensitive' trees under a perspex sheet (top of one of my Bonsai tables). The Moreton Bay is a very tough tree - nearly bullet proof, but considering the treatment this one got I'm not surprised it has lost its leaves and suffered some die-back. Might be prudent to check whether the soil has become water repellent through being dried out so much. If you can, dunk it in water and leave it in there for an hour or two to thoroughly soak the soil. Watering from the top only doesn't mean that the soil is getting properly moistened. Also, mix some Epsom Salts (Magnesium Sulphate) with the water - it is a good 'reviver' of sick plants, and is also useful after root-pruning and re-potting.
If you are not able to protect it outside, then sure take it inside - but put it in a sunny but draught free position. Don't prune off any dead stuff yet - wait till spring and see where the new leaves shoot from. If the branches have wire on them, yes, take it all off. If you really think you need some professional advice then try contacting one of the Sydney based Bonsai clubs, or if you PM me (with your suburb), I can give you a few addresses of some very experienced Bonsai people that would be only too pleased to give you some assistance.
Hope your tree recovers - Figs are great to work with. As an aside, While I lived in Darwin a magnificent Ficus Macrophylla won Champion Bonsai in 1991 - the leaves had reduced to about 15mm in length!