Ubuntu ruby on rails

Hi,

I am a php developer and I decided to learn ruby on rails.

I have a few question.

I have an ubuntu virtual machine with lamp.
It mean that it has alrweady php and when I access the ip of the machine from my browser it does load the index.php.

if I install ruby on rails will theere be collision between the php and ruby or the server just know that if I ask for ruby file or for php.

second I find this guide to install ruby on ubuntu:Blog of Ryan Bigg - Ubuntu, Ruby, RVM, Rails, and You

after I install ruby per the instruction in this manual, how can I know that I have done it correcty.

I mean I would like to access from my browser and see that the ruby on rails work and give me some "hello world" page, how can I do that?

thanks.