A: When your lease expires, then it is over unless you sign a new lease or fail to give your landlord a 30-day notice. Send your notice and move out when before the lease expires, which could be the last day of the lease.
A: You need to put all your terms and conditions in your agreement. You can use the same agreement for all three tenants, or more if you desire. Don't leave anything to supposition or make ambiguous statements. If you need further help, you can contact me here.
A: You will need to read your lease's termination section to find your answers. Without seeing your lease, I assume you need to give a 15 or 30 day notice in writing to your landlord. However, again, without seeing the lease, no one can give you solid infomration.
A: To be able to answer your question, I would need to see the SaaS agreement you have with your potential customer. I could then let you know your rights, and what you need to say in the Agreement to be fully protected and retain your data.