1.
Ruby supposes the source files to be encoded in ASCII, but the file
</usr/local/lib/ruby/gems/1.9.1/gems/feedtools-0.2.29/lib/feed_tools/helpers/uri_helper.rb>
contains a non ASCII character on the line 43, which results in a
parsing error.
Under Ruby 1.8 it was possible to define the source encoding using the
<-K> option or with the $KCODE variable. Under Ruby 1.9 they are not the
preferred way.
The source file encoding can be provided in the source code itself by a
comment:
  # coding: utf-8
Since I'm using Emacs, I simply write:
  # -*- encoding: utf-8 -*-

You can hack into the file mentioned above and add this comment on the
very top of the file.

2.
You seem to have compiled Ruby from source. Ensure you've done it with
the readline support. Search for <readline-ruby> using your package
manager, e.g.:
  $ aptitude search readline | grep ruby

-- 
Posted via http://www.ruby-forum.com/.