Noobie leadership question

[Hellebore]

I can't seem to tell in game how leadership works and I'm still kind of confused with the definition from the manual.

I tried disbanding my peasants and I noticed I didn't gain any leadership from doing that. So I am wondering, when I recruit a unit, do I spend leadership points like currency? Or will I have an ever growing pool of leadership?

If it is the case of the ever growing pool, can I then disband the units I'm using now and get my leadership back to recruit better units I find later?

Thank you