If the leak has been fixed: No you get nothing out of the delay. Their only legal obligation was to fix the problem & they have done that.
If it has not been fixed yet: There are specific procedures in each state that tenants must follow to force landlords to make needed repairs. The 1st required step in most states is to inform the landlord of the problem in writing regardless of if they know bout it or not. You need written proof they know about it before you can do anything. You failed to provide a location so you will have to look up your local laws.
Ask local educated adults for actual info locally in ur country as it varies greatly
Probably. Most leases have landlord responsibility in them.