There is no conflict between IE and FF, as long as you do not make either the default browser, and you can import your favourites from IE easily to become FF bookmarks. Since FF is a browser only (there is a separate E-mail application called Thunderbird), it will not interfere with Outlook.
FF has many add-ons(extensions) that will allow you to tailor your browser to meet specific needs.
You also need to install the two plug-ins--- JavaRuntimeEnvironment (MS's brand of Java will not work for FF) and Micromedia Flash Player.
See the FF FAQs here for additional information, features, etc.:http://www.mozilla.com/support/firefox/faq#plugins
I think you will find FF faster than IE, enjoy some of its more modern features, and rest easier knowing it is more secure than IE (and NOT part of your operating system).
Many members here use FF, so if you have questions, you can get answers by posting here.