7.5 mb download for this app. Looks rather heavy to me for a simple app.
It contains the contents of the .git directory and another copy of the .crx file, inside itself (who knows how many levels this goes down). Actual code (almost entirely jQuery and .psd "source" for the icons) looks to be ~100kb.
Authors, don't do this. git-archive is your friend.
No. Unlike Firefox, all extensions and tabs has their own processes. Go to about:memory on chrome too see the processes running