I've downloaded some plug-in's, how do you get them to work? I've gotten them in the data files, but, I can't get them in the game.

You have to activate them in your gamedirectory. ;)

start your game, in data file option check the box with the name of plugin.

I've been considering getting some of those plugins that replace faces, etc. with a wider range of characters.

Do these work well? Can they be opened into my current game without causing trouble?

Oru

Yes, they can.