Does anything change about these install instructions if I am just updating from the 3.0 version of

I currently have this plug in installed but a much older version. I need to be able to add multiple domain maps for one site, and went looking for answers and found this upgrade. I need to know two things:

1) If I am just upgrading do I follow all of these same install instructions?
2) Will all of my existing settings, etc for all of our websites that we have domain mapping done for now through the 3.0 version stick or am I going to need to go back into each site and redo it after install?

THANKS for your help! Looks like some great changes to an already awesome plugin!