How do the Horcruxes work?

[Inge]

No: HPFGUIDX 134983

First - appologies if this has already been asked and attempted 
answered. In that case I'd be happy to be directed to where to find 
them.

Voldemort creates his 6 Horcruxes and keeps the 1/7 part of his soul.
Voldemort is hit by the backfiring AK/spell/whatever and loses his body 
but keeps that 1/7 soul, right?

Voldemort wants immortality. But what happens if he's AK'd and loses 
that part of his soul which is presently inside him? He has 6/7 
soulparts hidden in Horcruxes - but how to get hold of one of these 
soulparts and get it inside him?

What to do when all 7 soulparts have been used up? Is that the end of 
Voldemort? If so - he's not immortal - he just has 7 lives - 7 and no 
more.

Or did I get the idea about Horcruxes all wrong?

Inge