We had a 7.30 booking and were seated inside, but when Illuminations starts they allow everyone to go on the terrace and come back to your table when the fireworks are over. We had finished our main courses so after the fireworks we ordered desserts and it was great, they didn't rush us at all. I was glad we had a table indoors as it was a very rainy night.
Regarding the 14 day ultimate tickets, they are definitely valid for 14 days inclusive so yes, you will need to choose which day to go, first or last. We had the same issue and I was back and forward trying to decide. We had 15 full days plus arrival day and departure day so, after much deliberation (!), we didn't go to the parks on our first full day, we went shopping, went to the pool, Downtown Disney (ate at Rainforest Cafe) etc so even though we got to WDW on a Tuesday evening we didn't hit our first park til Thursday morning. It actually worked out great though as we were really able to relax and just take our time on Day 1.
But one interesting thing is that on our last full day (Day 14 on our tickets) I was naturally hankering for more Disney and thought if we had the opportunity (i.e. valid tickets!) it would maybe be nice to go back to Epcot for an hour or so before our flights the next day. So out of curiousity I asked a CM at the turnstile about it and she said if we wanted to do it, we should go and talk to guest services at the front of the park and she was pretty sure they would allow us to come back the next morning for a couple of hours. Her words were "having had 14 day tickets, they wouldn't want to disappoint you and deny you a few more hours". As it happened we were under way too much pressure to get to a park on the last day but you never know, it could well work!
