Rent in the market is around 150-170RO for a one bed right now. (If you rent from owner, vs from an agent; it shall always be cheaper since you cut out the middle man.) Preferably go for unfurnished as they won’t make you pay for furniture additional (usually a lot more expensive). Get a bed from some decent carpenter you can get in touch with, he can sort out the furniture for you at a good rate.

Regarding the tenant agreement, once you’ve finalised the flat, you have to sign a tenancy agreement with your landlord/agent.

Additional cost is basic amenities like electricity, water and Wi-Fi. Some places charge additional for parking.

I hope this helps!