This is what I found out. I followed Iwfitz's instructions and everything installed ok. In the menu list it shows firefox title with Icewasel icon. Start Firefox it looks the exactly the same as icewasel.The only difference is at the very top it says Firefox in the header. With that being said, I am at a crossroad. I could try to uninstall both and try to install firefox alone, or, is there any real problem with leaving NoScript allowed all the time?