As a person who lives almost 18 years with CCHB (Congenital Complete Heart block, **congenital Complete AV-block) i can only tell you from my own experience.

I am almost 18 now, and even though my heart did not recover it self through the years, my heart works just fine, thanks to god! and i am sport active with no any restrictions.

More over, my condition and again thanks to god, does not require a pacemaker to be implanted.
How long a person could survive? well, i don't know it is up to god, but at least 17 years and doctors believe that people with CCHB live normal lives.

Last question - I just don't know.

So it seems that the initial questions were asked a looooong time ago, but for the sake of anyone else interested in knowing about pacemakers, i'll add my two cents:
I think in most cases of complete (third degree) heart block, the heart's conduction won't usually revert to a normal rhythm, but sometimes the patient's heart is able to keep a backup function going - some cells in a different part of the heart will fire to keep the heart pumping blood to the body. The worry is whether these backup cells give up...can lead to a cardiac arrest. So in most cases of complete heart block, the doctor will like to insert a pacemaker. This is especially so if the patient has been having symptomatic episodes of dizziness, etc.
A person with complete heart block and a pacemaker inserted can expect to live a full life as long as the pacemaker is regularly checked and changed when the battery runs low.
Pacemakers should be checked about yearly. If the battery starts to run low, this can be shortened to 6month or 3month checkups.