We have plenty of outages but for a different reason. We’re in hurricane territory but we lose power even during tropical storms or if we’re on the edge of the hurricane. So I can’t help with the heating because it’s an AC problem for us here.
It’s good that you’ve got plenty of flashlights because you want to make sure that guests don’t use candles - or you might want to get some battery-powered candles. Because he host mostly couples, we have the powered ones for a romantic ambiance to make the outage more fun. 
Make sure too that you have plenty of games, playing cards and books too to occupy the guests when they would otherwise be watching TV.
You or your co-host can contact the guests as soon as the outage starts and tell them that you’re getting in touch with your local power provider to get some idea of how long the outage will last. Make a note now of any useful numbers that you or the guest can use - local weather hotlines, local traffic info etc.
A lovely thing for you to do if there’s an outage is to call to see the guests with an emergency basket of goods - even more blankets, a couple of thermos flasks of hot soup, some cookies, sandwiches etc. Take a look at Amazon too and see what solar products are available - we have solar chargers so that guests can charge their phones or laptops. Make sure that the guests know where the first aid kit is in the house as they are more likely to hurt themselves with no lighting.
Sorry that I can’t help with heating - in our emergency packs I take ice!
Be sure to leave a message in the platform’s system too reiterating the lot.
I’ve never given a refund for power outages because they’re not my fault. When people travel, they should really keep an eye on the weather. I’ve found that guests quite like the ‘excitement’ of power outages as long as they’re treated with helpful concern.