1) The servers vary in terms of performance, support and extended features. You can read the specs on the official websites to find out more. Or google websphere vs weblogic and the like which returns
things like this
20 Yes, RAD is the IDE most closely integrated with WAS. If you want cheaper,
myeclipse has a plugin. Or you could use the totally free Eclipse and create an ear in
Ant or Maven that you deploy. Of course WebSphere itself isn't free, so there is still a cost. Or you could forgo WebSphere specific features and deploy on Tomcat (if you have no EJBs) or JBoss locally.