Tenants breaking the lease

[Yuliya Sonsyadek]

Current lease is through the end of August and my tenants informed me at the beginning of June that they would like to move out early. I have agreed to this stating that until there is another tenant in their place , they will be responsible for rent. I do have another prospective tenant that may move in July 1st. A few questions below: 

1. If no new tenant in their place by the end of their lease, are they legally responsible for the remaining payments? 

2. They want to do an informal walk through a week prior to move out , so i can point out what needs to be fixed and give them an opportunity to fix it. I was going to do it but wanted to see if there are concerns there. I dont want them to hold me to anything if i have missed something on this round.

3. They also want a formal walk-through on the day of move out, on June 30th , and on the spot determination of the security deposit holdback, if any, and return of said deposit. My understanding, i am not legally obligated to do this. I was going to do the walkthrough but not make any promises on the security deposit.

4. Can i also mention that the security deposit stays until there are new tenants? 

Thank you!