Model Railroading > Lionel Southern Crescent Limited Questions

I have just gotten a set of Lionel Southern Crescent Limited passenger cars used from Trainz Auctions.  Two questions:  I noticed the roofs are the darker green like the sides of the cars, but shouldn't they be black?  If so, is there a special paint that should be used to paint them black or would simply scuffing them and spraying work?  Also, these cars don't have transparent windows or detailed interiors.  Is there a way to convert them to detailed interiors?  Thank you for any help you can give.

Anybody out there that can help?