the point is: extensions are made to "freeze" customizations and not to be affected by core updates. if you wanna make sure that your view should be not affected by any core updates, copy the whole view and not only some template files or simply dont update the core or use a stable core version
if you update your core regularly follow our development changes on git and activities on the bugtracker.
yes, there is a changelog file inside the downloadpackage, so you can check the changed files there. or you can check the commit log on gitorious or on the bugtracker.
another way: clone your own repository on git and commit your changes there, so there is the possibility to send back good changes by a merge request into the core