1) Well, if you are new to an advanced photography and ND filters then I would skip them right now (but buy them if you want). Learning and understanding them might be frustrating in a rush, especially when you never used them before and you have only a couple of days before holidays. I know a person who started to learn on vacation and results were disappointing (for him and his family). Most likely you won't make a Hollywood movie from your holiday's footage, so the most important part is to enjoy flying, not being angry at your settings and lack of experience.
2) On the other hand I think it's good to learn how to use CPL (polarizer), it's easier to understand and use, drone might fly in Auto mode (it's not a disaster). If you know how to work with RAW/DNG files, then use them. Mind you have to turn the settings on separately for PHOTO and PANORAMA modes. Same problem with video resolution settings of VIDEO and QUICKSHOTS modes, they are independent.
3) I definitely suggest a sun hood for your phone connected to a controller. Bright sun = hard to see phone's screen + your sunglasses = you see nothing. Sun cover helps a lot.
4) Record on the ground video (with the help of your family or on a tripod) or at least record your voice while you fly. It might be nice to add it to your final movie if you plan to make it.