Legal Question in Civil Litigation in California

I assume both of your questions refer to situations in which a person advertises for a certain job to be done or item produced. When the job is completedly, then the contract is fulfilled, completed, finished, etc. Void means it has been set aside, gotten rid of for some reason; invalid means something is incorrect to the point of being entirely wrong as to the assumptions upon which it is based. Neither term applies to what you are dicussing.

Once all the terms of a contaract are completed, the contract has been finished and no furhter work is required. A time schedule is used if completion by a certain date or time is needed.