What is the ruling on delaying ghusl and prayer when there is a continuous discharge of pre-seminal fluid or urine between different prayers, or delaying ghusl from a wet dream when there is a continuous discharge of pre-seminal fluid, awaiting the cessation of their discharge, knowing that the time of their cessation varies?

The meaning of "does not cease for a time sufficient to perform the prayer with a valid purification" is that the discharge continues such that if one were to wait for it to stop, the prayer time would expire. If the woman experiencing the discharge has a regular habit of the discharge stopping, she should wait until it ceases. However, if her habit is that it does not stop, or if her habit is irregular, she is not required to wait; rather, she should purify herself after the prayer time begins.