You insert the ROMs first then install 3.1. Are you aware how to install them and were they go exactly?
as for the 3.0 > 3.1 Intallation, you should be able to overwrite your 3.0 partitions but I wouldn't know for sure as when I upgraded to 3.1 a few years back I did a fresh install. If I were you i'd do the same and just back up stuff you want to keep.
About the RAD stuff, I wouldn't have a clue.
