for TVB, I think it's worth if you still concern the news about HK. For leisure, it has the same time dramas with HK. Now the spending in Sydney is very high, just think it only worth one time "Yum Cha" in city! But if couples need to go working, may have no time to watch! My friends' families some have eldery grandma/grandpa, then it will be perfect. (
(For installation, house should be no problem, but for apartment, it depends the strata.)
Foxtel is more expensive. Hardly to tell how much, it depends on how many channels/services/what kind of set top box do u want to get. Also, telstra has some bundle packages which includes Foxtel. Try to look at their website. Mine one is about $50 per month includes sports channels, it's cheaper, because we are old customer and they are giving us special offer.
Thanks very much for all your advices. I decided not to install it now because I am currently renting a house and I don't want to pay extra for relocation later on.