Sure you can. I used to, back when I was taking classes online, I had to have IE to access the class website, but I would do the rest of my stuff in Firefox 3 without any problem. Firefox can also be easily uninstalled, too.
Yes. There are even some Firefox add-ons that support it!
I personally use them both at the same time all the time. Some sites I frequent only support IE7, I use Fire Fox for the rest.
So yes, they'll both work at the same time. You can uninstall Fire Fox if you don't like it with basically no pain.
yes you can use both of them at the same time.and you get no problem while uninstalling firefox
You can also use Safari if you like it