Hey. I know it is quite difficult to find a teaching job here as I have met a few people who have been here for, literally, months and have yet to find a secure job at it. They are teaching during the weekends, but as for a full time job, you will need to research a bit.
As for finding a roommate, I'm guessing you are looking for company/price efficiency. I'm staying at a youth hostel at TST (nathan rd) which is a fairly good location (near MRT, ferry etc.) and you can request staying a dormitory-type room. The price is 60 HKD (about 8 USD) a night and from my experience, the travellers who stay there are very interesting people--some who are staying there long term too.
The name of the hostel is New Garden and Kowloon hotel. The quality is fairly low, but you get AC, cheap laundry service, and a place to stay, which is fine for me.