Current Web site

Newbie to WordPress.

Have not done anything yet still researching how it all works.

I have several sites already up and running. Most hosted through Godaddy one through Yahoo.
All the sites for each hosting company host the website and the domain name.

Godaddy I know I can use WordPress with. Have not looked at Yahoo yet.

Here is my question:

How do I maintain the current websites and still get wordpress installed and up and running?
Once all that is installed Can the current sites still be used while I create the new sites using wordpress?

Bob