1. Does nginx spdy module is enabled by default?
2. Sometime ago you said that Ruby 2.0 has some bugs you suggested to wait for next Ruby 2.0 patch release. Is this still the case?
1. No, but you can easily enable it by yourself by choosing option "(2) I want to customize my Nginx installation. (for advanced users)" in passenger-install-nginx-module. Arbitrary Nginx configuration is fully supported. We're going to enable SPDY by default in a future versions.
2. Yes. Phusion Passenger 4 fully supports Ruby 2.0 so it doesn't prevent you from using it, but you may run into Ruby 2.0 bugs, e.g. https://bugs.ruby-lang.org/issues/8100. We recommend staying with 1.9.3 until the next Ruby 2.0 patchlevel, but the choice is yours.
2. Yes. Phusion Passenger 4 fully supports Ruby 2.0 so it doesn't prevent you from using it, but you may run into Ruby 2.0 bugs, e.g. https://bugs.ruby-lang.org/issues/8100. We recommend staying with 1.9.3 until the next Ruby 2.0 patchlevel, but the choice is yours.