Emergency Contraceptives

It's hard to answer your question. There is no way to know how much of the drug is still in a woman's system a day after taking it.
For the second part of your question, if the woman has not already ovulated, the pill stops her from releasing an egg. I do not know if this delays it for one day or until her next ovulation.
Here is a direct quote from one website
It works by:
Stopping your ovaries from releasing an egg
Preventing sperm from fertilising any egg you may have already released or
Stopping a fertilised egg from attaching itself to your womb lining.