some of the plugins depend on the spark source code being avaialble in a certain path. if you are not working on those existing plugins, you can simply remove them from your build path and eclipse should be happy.
Right-Click the plugin source folder --> Build Path --> Remove from build path
The error about the updater part is related to you not having install4j on your system. spark using install4j for launching and requires the install4j.jar to be present.