If it can be done.

New adds to the playlist - No restriction to the number of plays.

After 14 days - No repeats in 36 hours (I think that's a better time differential. If someone is RQing the same song it would mean that the next time it becomes available to RQ would be in the middle of the night for them but it would mean that peeps in, say Europe, who want to RQ that track could do so at a sensible time.)

Limit the number of RQs per person in any 12 hour period to 4.