Finding out how much the rent or the how many toilets in the property are important but the most important information you need find out are:
How is the Landlord? Is he a living in landlord or living out landlord?
If the whole property is rent, example a group of friends a renting a flat or house and then sub letting rooms to cover the rent , you must find out who is legally named on the contact ?
If you are renting from an agent, ask many questions to understand the property situation and your right in case something not right
Also you need to know some financial arrangements, example,
Who do I pay the rent to?
How is holding my deposit? How long notice you need to give to get the deposit before leaving the property?
How responsible for paying for gas, electric, net,..?