title: Firefox extension testing and developing - I'm confused
body: <p>when I'm writing extension for Google Chrome, I only create "manifest.json" file and  JS file, which is my script. after installing ,   I can change anything in the code, I only refresh browser and I had changed version of extension. </p>
  
  <p>1) Can I change some code after installing Firefox extension? Or should I reinstall it? Or should I need to reload it again - and how if its possible?</p>
  
  <p>2) should I create  install.rdf, chrome.manifest,  *.xul  files and so in by hand (whick folder structure and so on)? Or is there another simplest way to do this?</p>
  
  <p>3) I don't understand, should i create extensions by  "Add-on SDK" or write by hand with notepad? what is difference of them? </p>
  
  <p>4) I'm writing simplest script, which invoke alert('hello world') when i open any page by browser. what is the best and fastest way to do this? </p>
  
  <p>thanks a lot;</p>