5 RVM by Wayne Seguin allows you to easily install, manage and work with multiple Ruby environments from interpreters to sets of gems and it’s a must-have tool for modern Rails developers. http://rvm.beginrescueend.com
6 Comically, the Rails inflection of virus is also wrong. See http://en.wikipedia.org/wiki/Plural_form_of_words_ending_in_-us#Virus
9 Yehuda’s take on the subject is essential reading http://yehudakatz.com/2010/08/14/threads-in-ruby-enough-already ...