TOPIC: Closing the project

Hi everyone,

I have read couple of questions regarding closing and get confused:

1- In the closing part if the client ask for sth which is not included in the contract, could we use change log and add that one as a scope?
2- After the closing part could we do change log if the client asked?
3- If after closing any defect happened to the project? we have to fix it? are we responsible? any warranty?

Regarding Agile:
If the client ask for extra feature, should we add it in the next itteration? do we need to use change log?

Thanks