Do you have support agreement with Adobe?

You will need to contact Adobe support to get new certificate 

 

Do you mean when you open the form in Designer V9? This article has information on the impact of expiring Reader Extension Credential

Adobe support 

What kind of form?pdf?

In the servlet, you can access the entire data and parse the XML to get hold of the element that you want to access For example, in the following code, we write the request parameters and their values to the log file.  System.out.println("form was submitted");Part attachment = request.getPart("attac...

It does mention installing GIT later in the tutorial 

For number two you will have to do USA= USA or just have the country name  

https://experienceleague.adobe.com/docs/experience-manager-learn/cloud-service/forms/developing-for-cloud-service/getting-started.html?lang=en