Rails <selection>, config.yml etc

Actually I have more than one question, If you give me some advice or
idea I will be really happy. I m newbie on using Ruby. I have just
stared writing program with ruby and ruby on rails.
fist I want to ask about preparing config.yml file and read it in
selection tag. I want to create config.yml file which is including some
paths and names, How can I create it and use them in
tags, the value of the option I want to get from the config file I
Another question is about config file again, for example I have 3
datas in config file that used in selection tag. I want to check the
number of datas in config and if I have change in config file I want to
see it in selection, like if I delete one of the data, want to see 2
I told you more than one question, I was also wondering that can I
assign two action to button in rails. I want to run converter and save
the result. is it possible?

I also want to learn using ruby.rb files in rails. Is it possible to
use Ruby.rb files in Rails. how can integrate the ruby project to rails?

another curiosity that where the rails use database.yml datas. how
does it call?

the last question is connected with the others actually, I have
program which take datas from database and convert to XML. I run it in
windows commend line. program takes some argument to run . date, id etc.
how can I integrate it to rails.

I hope the questions are understandable. I really need help.