My friend made a pretty sweet cleric deck that uses the infinite life combo and I am trying to understand it completely, so a few questions if you all don't mind. I understand that one could play the ability and give his/her cleric +0/+2, let it resolve then do it again and again, then play the starlit sanctum for life. Now, if someone decided to use one stack and do the ability over and over then use the starlit sanctum in the same stack, would the +0/+2 abilities resolve or would they only get life based on the original toughness do to the other abilities not resolving?

Another question I have, my friend mentioned that "the game action of the sacrificing the creature starts a new stack and the life gaining ability is on that stack", is this true or would it just fall into the current stack that is taking place?

Thank you all in advance for any information you can provide.