Receipt number and then chances for approval

My employer informed that the checks issued to USCIS were cleared (cashed) on April 22. It means that the petition is selected in lottery.

But still attorney or employer have not received the receipt number. How much time it take to give receipt notice / number?

After selecting in lottery what are the chances of “rejection” in later stage / process? Can we assume that there are 95% chances to get petition approved?