You can have multiple projects open in IntelliJ. When you open a second project, it prompts to open it in a "New Window" or "This Window". The confirm dialog has a "remember" option, which you can reset under Prefences -> General -> "Confirm window to open project in".
IntelliJ can also download Maven sources + javadocs automatically via Preferences -> Maven -> Importing -> "Automatically download". Otherwise, you can download manually by selecting the Maven Projects tab and clicking the download icon. Opening a Maven project with IntelliJ is really easy: just open the pom.xml and it will automatically create the IDE project.
IntelliJ can also download Maven sources + javadocs automatically via Preferences -> Maven -> Importing -> "Automatically download". Otherwise, you can download manually by selecting the Maven Projects tab and clicking the download icon. Opening a Maven project with IntelliJ is really easy: just open the pom.xml and it will automatically create the IDE project.