Moving to Phnom Penh Nov 17

Hello all, I'll be moving to Phnom Penh for a few months of work on November 17th. Seeking advice on housing:
Is there an expat area distinct from the tourist area?
Are guest houses cheap over a 3 month period?
Anyone know someone who needs a roommate for 3 months?

Advice on resources for the city...is there a google group or some online resource that is useful?

Cheers, would be really helpful. Thanks everyone.