We have always visited a PCCW shop to renew contracts, so that we can read what we are getting in writing before we sign up. This was the first time in 10 years that I discovered 'surprises' on our bill.
Sorry, I don't know much about the 12-month or 1-month roll-over options except that they are definitely more expensive than the 2-year contract prices.
I recently discovered 'Early Termination Charges' and 'Charges for loss, replacement or failure to return equipment' (HKD1000+) on our last contract, which I hadn't noted before! From now onwards, unless we can read Chinese, we won't know what we've actually signed up to!
Honestly, if you have a choice and want to avoid headaches, I suggest you give PCCW/NOWTV a miss and check-out the other TV providers in HK. Good luck!