Arrival at hotel??

Yes you need to show your passport but you can keep it. Visitors to your hotel depends on the Hotel / Guesthouse rules and regulation. Reg. Mike

Hi
Copy of passport or I'd is required but not same as Vietnam;
Companions are generally welcomed in Cambodia
With discretion  and no fan fair;
Come to Cambodia and you will be welcomed and respected
Mjk

Thanks now i am feeling confident. In General do people leave the passports in hotel room or carry with them

Up to you, just make sure its secure. Perhaps keep a copy in your pocket. Reg. Mike

Perhaps this will help you. If I travel outside my home town Siem Reap I deposit my Passport, cash and credit card in the hotel security box. I only carry a cash card (limited amount) and some spare cash with me as well as a copy of my passport and visa if required. If you loose or your cash gets stolen what you have on hand you want be much in problem. simple rule and applies to all my travel.  Regards Mike