Streamline Upgrade; Old NightHawk to New NightHawk

No. You'll need to take screen captures from the old router and use them for references on the new one. 

Only NG would have abilities to decrypt backup cfg files. 

Understand that though some of the features maybe similar or same between routers, it's FW and other system differences that cause cfg files to not be compatible. So NG keeps models with in models and tied to there cfg files and doesn't make them specific. Making a cross compatible cfd could bring opportunities for errors and problems in system operation and instability. So if a new router needs to be setup, needs to be done from scratch. Been like this for years and seems industry wide.