1. You can duck bf3. Just don't block, goes right over. Punish with Shadow Kick.
2. Do not try to outfootsie Kung Jin, Sonya and Liu Kang are the only ones that can try. Learn his spacing and punish when you feel comfortable. Most Kung Jin players get too antsy about jumping in - backdash and punish.
3. You always have to be aware of a KJ's meter, if you are caught slipping, you're catching a (what should be) mb bo swing to the face that tanks a hit. Neutral Jumping is effective for this as the armor doesn't tank air attacks.
4. Kung Jin does not lose in "closer than bo reach", he still has a 11 that's 9 frame start-up and is 0 on block, 34 on hit. This can lead to overhead or low that are both safe and he can end with db4 for an overhead, splat ender.
Your best bet is to play slow, stay just out of jump in range and punish. Remember, his divekick doesn't angle very well, it's basically 45 degree angle. So It's flight path is damn near equal to just jumping in.
Best of luck.