1. Buy your tickets the day before, so you can double-check the weather before you purchase them. I think you just call MS if you are wanting the
DVC discount and then pick them up at your resort. Someone correct me if I'm wrong. I made the mistake last year of almost forgetting to call MS. We were at DHS and I realized MS closed in 15 minutes. I didn't have my cell phone with me, so I ran to the front to Guest Services to use a phone. Then when I got there, I realized I didn't have my credit card, that my husband had it. I had to settle with Advance Purchase tickets, so I got them for cheaper but not as cheap as I would have with the DVC discount.
2. I would definitely go on a different day than your MK day. In fact, I would recommend not even going to a park that day. You can get in at 4:00 with your
MNSSHP tickets. What we did last year was sleep in, have a late lunch at Whispering Canyon, and went into the party at exactly 4:00. We were able to do everything we wanted MANY times! Next year, we are planning on doing the same thing except we will have a late breakfast at Boma instead. VERY RELAXING DAY!!!
3. Not everything is open, but most of the popular rides and restaurants are. Someone may be able to help you with a link to a list.
Hope this helps somewhat.