HK-47 does tell the Exile this when he/she asks him if Revan was training Jedi and converting them at Malachor.
I don't understand the difference between a Wound and an Echo. What do you mean when you say it "resonates with other wounds"? And you said the echoes do something to the Exile but he/she only becomes stronger. What does that mean? Kreia thinks the echoes can do good things too? What do these echoes have to do with the Exile's bonding ability? He was good at bonding even before Malachor right? Did he drain the Force from the others then too?
If Nihilius has difficulty in sensing the Exile and the converse is also true, then in the game why does Kreia ask us, "Have you felt it?" And we reply, "Yes, it's Visas' master", and then choose our prestige class?