Weblogic server created based on j2ee standard , weblogic.jar file is the core of WLS ,IT has all the class of weblogic server .
for that you need to set the classpath ,
weblogic.xml if the deployment descriptor file for weblogic server . it has the information and configuration properties of your weblogic application module.
2) you can deploy the application in exploded format if you deploy the application partialy and you can update the static condent like jsp,html,jpg files at the time of access the file server automatically update the newley updated static condents rather than its not possible in archived format deployment . you can get more information from weblogic docs.