You are probably missing a font, or your new version of Finale does not know where to locate it. I'd start by checking the Music Font assignment in Documents and in Documents > Options> Fonts.

When I open a part done previously and add more staves, when I input new music on the new staves the music spacing crams things together. How do I keep my spacing?

Do you have Automatic Music Spacing turned on? Have you tried selecting all, or a section, and applying music spacing?