Dumb questions - WPMU and hosting?

Hi team, I know this information must be out here but I have done a few searches and not come up with the answers. Two part question:

My site is modernsingleparents.net

Part 1

I am not sure if I'm using WPMU, and what that means. I want my members (we have nearly 4000) to be able to have their own blog. At this point, we just have one blog that houses our magazine articles. Is this part of the WPMU and if I don't see this option in my dashboard does it mean I don't have WPMU?

To accomplish the goal as stated above, what is the best way to go about it?

Sorry if this is a redundant question and the information I needed is only a click away. Can you point me there?

Part 2

I am hosting on Godaddy.com and I'm told that it is slow. Is there another host you can suggest, as well as a service that will move everything over to the new host that I can pay for?

Thanks!
Clare