1. Depends on practice; I might use newer to figure out reaction differences so I can make ball changes easier. If working on mechanics, I'll use a different ball sometimes.
2. I'll have a ball resurfaced periodically, maybe once per year..
3. I just use a simple hot water/soap bath to clean when needed. For me, When needed is ball motion thru pins. If I start leaving "plastic ball" flat 7's, or if the ball isn't turning the corner right, sure sign to clean.