Recommend and reputation

Hey guys,
reputation is gained uppon killing karma players right ( and your name become green) ? but what are recommends needed for?
In the end what does these 2 social things do? what we gain from them ?

nothing, recommends just change your nickname color to blue (assuming you don't have positive rep and are green, in which case they do nothing)

For a few months back before GoD, the more rep you had, the more XP you received while out XP'ing for the first hour of the day. They changed that back to it meaning nothing, except a blue name as it was by far the easiest exploit they could have created. Everyones names stayed dark blue becuase everyone would team up and rec each other back to full, or use their boxed accounts to get their recs back to full.

so recs are lost over time ? in what stage they become blue ?
it seems that i have to kill a karma one for a goodlooking colour :P

255 recommendations for a full blue name.