Jack is a factual space/time anomaly that wasn't supposed to have happened (in reference to Rose bringing him back to life forever). Watch the episode "The Last of the Time Lords" a little more closely and the episodes that precede it (Utopia and up). The Doctor tells Jack as to why he runs away from him. What's more, it says in the episode "The Empty Child" that the Time Agency erased two years of Jack's memory, and Jack doesn't know why.
It's Harkness, although that is not his real name, he stole the identity of the real Captain Jack during WW1. His real identity is unknown.
Captain Jack had a relationship with Ianto Jones in Torchwood. He's also kissed other people like Captain John who is his ex. On Doctor Who he kissed both the Doctor and Rose.
No, there has never been a young version of Jack in Doctor Who.
Captin Jack is a fictional man, from the BBC series Doctor Who and Torchwood.
Yes, Captain Jack Harkness asked the Doctor about what happened to Rose Tyler after she was trapped in a parallel universe. The Doctor informed Jack that Rose was safe and happy in the parallel world with her family.
At the moment there are no plans for him to return to Doctor Who.
The 9th Doctor, Jack kissed both him and Rose before going off to fight the Daleks in The Parting of the Ways.
John Barrowman played captain jack in doctor who. :)
Cristifer Ecelson in the unborn child
I know Captain Jack is of christian culture.
It was Captain Jack Harkness.
That is a very subjective question. Any answer would be the person's own opinion.