Hi Danielle! Welcome to the the world of running! I think it is definitely a good thing to be addicted to!
RunDisney is amazing! It's especially perfect for new runners looking to begin entering races with low pressure, and also looking for their first long distance races.
Registration for the Expedition Everest Challenge is slated to open in late fall. I would look at early December to be when it opens up.
My two boys and I ran it this year with my sister-in-law and LOVED it!
Most runDisney events will offer host resort discounts of around 20%-30% off regular room rates. I don't know for sure if the Expedition Everest Challenge will this year, but travel information will be posted on the
runDisney website with packages and how to book. Definitely consider staying at a host resort, as these are the ones that will provide free bus transportation to and from all of the race weekend events.
Please let me know if you have any other questions!