I suppose.
I say this because Lucy may still consider Kouta a friend so yeah, that's why I say that there may be hope yet. 
Oh definitely. He's always going to be one of the most important people in her past, but whether that's reciprocated depends on him and...well, he has every reason to not reciprocate unless she's Nyuu.
It seems hopeful than her previous friend which was nothing more than an utter traitor, I think that Lucy would understand if she knew it was his sister he was seeing but again, all depends as you say.
Her seeing Aiko again would be nice too, now that I think about it.