Residential stickers are free, but you are not guaranteed a space near your house. Guaranteed spaces are rarely included in the rent. Figure into price if you will need a T pass each month. Note that it is illegal for the landlord to charge you for water itself, but you will usually pay to heat the water. The local police department should be helpful.
Many landlords require first and last month's rent.
Some landlords also require a security deposit when you sign the lease. SAGE is the group that addresses the issues and concerns of graduate students in the College of Engineering.