Modernising a 90s Warhammer 40K Army
You would need the core rule book and codex to start.  Both the Dark Angels and Blood Angels codexes are separate books now.  There are scenario cards and psychic cards for the current edition, but they are optional.  The game currently uses the 3" and 5" templates along with the teardrop flamer.  Those, a measuring device, a scatter die, and copious d6s is all that is required for play outside of minis and terrain.  

The special characters available have changed much since 2nd edition.  The big ones like Dante, Mephiston, Ezekiel, and such are still around.  Generally if a character has gone away, there is usually a generic HQ options that you can still use the model for, such as a Blood Angel Sanguinary Priest and in the case of Bethor Dark Angels chapter standard bearer.