@Roxy, welcome to THS Forum. @WeRPAWsome has given some great questions.
Our whole approach to video calls has evolved materially through experience. Initially we had employer-employee mindset and let PP ask us questions in manner of a reactive interview. We found that ineffective as we encountered surprises, on topics that we had not asked about. Ugh. We now proactively approach video calls as peer-peer exploratory conversation on preset topics … situation/travel (where, booked, PP dates, HS dates, etc) and on pets (details, care, exercise, food, medication, typical weekday/weekend day, etc).
We find that PP ask us surprisingly few questions during video call 
. After our proactive conversation steering, most PP have gained comfort that we have experience and diligence … and we have gained info to assess fit, opportunity and appetite to aid our decision to confirm any offered sit 
But some PP have specific needs and should seek related info. Could be pet medication (we’ve had a few of those) or property quirks (location, facilities, community) or travel logistics (specific dates, vehicle). Questions probably vary depending on housesit duration (3 night vs 3 months) and other factors.