Where are you executing CouchDB (AWS, Google, Azure, Installer in Linux or Windows, etc)?
Which CouchDB are you using?
Anyway we are currently offering the latest stable version of CouchDB 1.6.1. CouchDB 2.0 is not yet considered as stable and, as far as there is a major version change, there are compatibility issues between the two banches 1.x and 2.x. As far as i know CouchDB has not provided a guide or method in order to migrate data from 1.x to 2.x yet.
In order to install Fauxton you just need to follow this steps:
sudo apt-get install npm
sudo apt-get install node
sudo apt-get install git
sudo ln -s /usr/bin/nodejs /usr/bin/node
sudo npm install -g fauxton