Yes. A parking space will generally run you between $100-$200 so if you don't require one then the lease will be noticeably lower. Some tenants are under the impression that with all things being equal except that one unit has parking and the other doesn't, the asking prices will be the same. This is wrong - prices will factor in parking.

Depends. If the lease includes parking then the landlord will unlikely lease them separately - too much inconvenience. An alternative would be to lease the unit and you would sublet the parking to a resident of the building.

First, keep in mind, that the two units are most likely owned by two different owners. With all other things considered equal, landlords have different thoughts towards the price. Some place their unit below or at market value to avoid vacancies, whereas others do not mind if their unit is vacant as long as they achieve their price. If a unit is overpriced, it still may be worth it to throw them an offer with the lower price.

If the landlord requested it when you applied for the unit, you must provide such a deposit. However, it is illegal for a landlord to demand or to collect a rent deposit of more than one month. Also, it must be used for the last month's rent. It is a violation of the law to use it for anything else, such as to pay for damages. Once you are a tenant, you do not need to provide one, unless you agreed to do so before getting the unit. The landlord must pay interest on the rent deposit every 12 months at the same rate as the rent increase guideline (e.g. 1.4% for 2008).