That's the key right there to being Shaka's buddy... you do the above, Shaka is your friend for a very, VERY long time!All the warmongers are pretty similar - share a religion and fight the same person as them, and give them what they demand, and they're friendly before you know it.
This means keeping an army, so their target isn't you, and actually attacking someone.
Not quite. Shaka values religion very little, so you won't get a huge cheap diplo bonus by sharing his religion. There are other peaceful factors that give you a diplo bonus with most leaders, but not with Shaka. And if you share borders, it's even harder because you get a massive "close borders" penalty very quickly.All the warmongers are pretty similar - share a religion and fight the same person as them, and give them what they demand, and they're friendly before you know it.

It lasted the whole game.
Like mentioned Gilgamesh I always seem to be able to be friendly with 
indeed) as he doesn't open borders and rarely has a religion! Only ever got Friendly with him due to him vassaling with me.
Shaka is a good partner if you can be friendly with him. Just watch out in case he tries to DoW on you and back stab you.