Other hospital policies (doctor's policies are a different bag) that are important to ME and I would inquire about is frequency of vaginal exams, options for group B strep treatment if you end up positive, food and drink in labor...
Doctor's policies that are of value to me is when they use pitocin in labor, how long they'll let you labor without using something like pitocin (12 hours, 24 hours?), their belief on episiotomy use, their support of delaying the eye ointment and vitamin K shot for 60 minutes or until breastfeeding is established,
I make a big show of important to me, because what is important to me in a hospital labor may not be that big of a deal to you....and I would never want you to feel like if you choose something different than me that it is wrong - any informed choice is the right choice for you!
Another question I would ask a potential doula (or as a doula, that I ask my client!) is what other childbirth preparation are they planning or have they done. Childbirth classes given by the hospital can sometimes be more about "how to be a compliant patient" rather than really teaching you coping techniques. I encourage my clients to take an outside childbirth class (Lamaze, Bradley, Hypnobabies, etc) or read intensely about styles and practice with their partner and myself about how they cope with labor.