Just to ease your mind a bit. We were at the world last October during Matthew. Obviously Irma looks to be more intense. But our experience was as follows:
They announced they were closing the parks at 5pm through text msg, loud speaker announcements, and on
MDE at around 11am. We enjoyed the park for a few more hours and then headed back to our resort.
The food court was chaos!! So my suggestion is to stock up prior to the storms arrival. Water, snacks, etc.
The resort did a fabulous job of keeping us informed through the phone msg system. We felt 100% informed and safe. As a matter of fact we slept through the worst of the storm. There was a curfew in place from 8pm until about 11am the next day. They had a shelter in place -our room- that night. We went out around noon and explored our resort, Pop, and AoA, had some lunch and then they announced that Disney Springs would open at 2. We did go but it was so packed we could barely move!!
Disney did a great job keeping us informed and safe! You will be fine! Take rain gear and enjoy the parks as much as possible for as long as you can!! I agree with pp, no candles. Take a flashlight. Our power never flickered.