[kingnothing]

1. Unless you're switching programming paradigms, learning a new language is trivial if you have a copy of the API to reference. It's all just syntax and libraries at that point.

2. Do it when you're comfortable with the language.

3. Why would you learn a new language if the one you're familiar with is the right tool for the job? I can only assume you're looking to pick up Ruby on Rails or Django instead of PHP. From my experience, Rails development is orders of magnitude faster than PHP if you're using it for the right project.