We encourage you to wear Tolkein-Inspired garb (think Renaissance Faire or Medieval times), but it is not required. If that isn't your style, standard semi-formal attire is perfectly acceptable.
It will be a buffet style dinner with options for gluten-free, vegetarian, etc. We are trying to be conscious of most common restrictions, but if you have a specific need, don't hesitate to ask and we can be sure to work something out for you!
Maybe? The ceremony is outside, but umbrellas can be provided by the venue if needed. We would suggest having a coat or something similar on hand just in case. Seattle in October can be unpredictable. The reception will be largely inside.
Yes, however there is a cost (less for self park, slightly more for valet). If possible, we suggest carpooling.