I got the idea about the income tax from this thread here:
http://www.justanswer.com/tax/2km9z-...ment-rent.html
"If you and the room mate were paying rent to the landlord directly together, then you do not have to report income.
However since you pay rent to the landlord on your lease with him, and then rent space to a room mate, then you have to report that as income.
Likewise, if it is your lease and rent obligation for which you alone are obligated, and the room mate pays the landlord for you, then you still have to report it as income.
In order to avoid this as income, you and the room mate have to be legally obligated for the basic rent and pay your fair shares to the landlord."
So as a landlord, when you require everyone to be on the lease, you don't really care who pays the rent or in what percentage as long as you get the total amount on time? On the application for the apartment where I would like to live, it has one section for the person applying for the apartment who will be the leesee, and then another section for people simply occupying. This implies that only the leesee would be responsible for the rent and the others are just occupying. But perhaps I am wrong and if the leesee defaulted they would try to get the rent from one of the occupants instead?
Ultimately it is probably just going to come down to me asking the landlord about it. Thank you for your insight so far!