XML names are just for our identification purpose, means by seeing the name will come to know that whats the use of that xml file or what does it contains.
Say for example
applicationContext.xml - Will tell you that contains information related to your applicationContext.
mvc-servlet.xml - MVC related configurations.
database.xml - database related configuration.
For your second question, i mean how to change the default <servlet-name>-servlet.xml in Spring MVC.
Do like this:
Instead of giving your mvc configuration file as a <context-param>, give as a <init-param>.