I had trouble figuring out what to do at 10 inf with HK too. The lightside walkthru doesn't tell you to get that last drop to 2. You'll have to dig but eventually you can say to him, "I can't allow you to remain on this ship if you've killed Jedi.". This will allow you to respond with, "How can you respect death on such a scale?". That will get you the last inf decrese you need with him.
In regards to the rewards for HK -
After scouring the dialog tree for HK, I couldn't find where you can get the extra +1 con/wis. The first lesson triggers the script "a_hk47jedixpaw1" which gives +1 reflex + 1 con (the +1 wis +10 force points is commented out); The second lesson triggers the script "a_hk47jedixpaw2" which gives +1 wis +10 force points (the +1 con +1 reflex is commented out). I see no way to trigger these scripts more than once each (unless I'm missing something that will reset the global variable allowing you to get these dialog option again). If some versions of the game don't have the extra bonuses commented out, then you would recieve the double whammy. It would be interesting to know if that is the case.