Do Bundled Plugins Get Updated When Updating Elgg?

Hi, I have two questions: 

1. Should I modify the bundled plugins if I want to make changes to the views for example. My understanding is that the bundled plugins are not part of the core we are discouraged to modify. What I do is I make a copy of the bundled plugin I want to modify and then make the changes I want in the copy of the plugin?

2. If the bundled plugins are not part of the core files, then how do they get updated if elgg makes changes to them?