Great questions however the best way to answer this is to look for yourself from what I can send to you I have access to a paid online service that gives the history and current rents of houses & units I`m happy to send it to you which will help you a lot
Bronte is definitely getting more and more expensive. The further away from the Beach though, the more reasonable priced. For your convenience you probably don't want to be right at the beach anyway as it doesn't have much to offer in terms of stores, doctors,... you would always have to travel up the hill. Public transport is good with the 378 running all the way down to the Beach, but again, more frequent and diverse Busses are all up the hill. So to me a rental apartment in Bronte should not be more expensive than one a bit further up the hill - at the moment you're looking at over 600/week (more around the 650/700 mark) for a two bedroom apartment that is just average with no standout features like seaview, all renovated... . I have no idea about smaller or bigger places.