[quote]can I go back and beat each mission on lego to get exotic armor?[/quote] Yes [quote]do I need to farm the lost sector du jour to unlock new exotics?[/quote] You will need to farm lost sectors to get the other exotic you didn't pick, after that they can drop normally (ie Xurs engram/exotic engram drops etc) or you can continue to farm lost sectors Exotic armor from beyond light and on you need to do lost sector to get