This is really only a part1 answer, and I also suggest splitting this into 2 questions.
The key to using different IDEs is to make sure none of your build/code is IDE dependent. The most typical problem is that you check in the file containing the application's classpath (the .classpath file in eclipse for example). Instead, you should use an external dependency management system such as maven or ivy (ivy works if you use ant, but maven is both a build tool AND a dependency management system so I would recommend maven if you can). Any IDE worth its weight will have plugins to support ant, ivy and maven, so as long as the developers have the plugin, they just point to the appropriate ant or maven build files. Maven's website is http://maven.apache.org/ and Ivy's website is http://ant.apache.org/ivy/.