As much as the park freak in me loves getting there before opening to see the opening ceremonies, it tends to be exhausting throughout the course of the day. However, with MK, you for sure won't be able to get everything in that you want to see without being there early.
On the 17th, Wishes (to my memory) is at 10pm with the electrical parade at both 9pm and 11pm. Best spot for fireworks is right in the hub (the roundabout centered around the Partners statue) to the right of the Partners statue, facing the castle.
For dinner, with your price specifications, I highly recommend making a reservation ASAP for The Plaza restaurant. It's not very well known, but the food is surprisingly good and for a table service restaurant, it features some of the lowest prices on property. I've eaten there several times.
Basic info:
1. Take advantage of the Fastpass system. You can print a new Fastpass for a different attraction every 2hrs, regardless of your return time for the Fastpass you currently hold.
2. If you're getting there early/before park opening, it's tempting to head right into Tomorrowland and start doing rides. However, my recommendation is to grab your Fastpasses for Space Mtn. and immediately head over to Adventureland. The crowds almost always head to Tomorrowland first, so this way you avoid long lines in Adventureland while still having your Fastpass ready for Space Mountain later in the day.
3. However, if you choose to not do the aforementioned plan, head into Fantasyland after grabbing your Space Mountain Fastpasses. By doing this, you ensure that you'll be able to experience Enchanted Tales with Belle with little to no line. The attraction commonly rivals Peter Pan's wait times during the day.
4. Be at Be Our Guest early for lunch. It fills up very quickly and it is not something you want to miss out on.
5. Don't feel stressed to see the first showing of the electrical parade. If I recall, May 17 should have two showings, and the showing after Wishes is always less crowded.
6. Make sure you grab a Dole Whip at Aloha Isle (Adventureland) at some point in the day!
With the attractions you specified, you should want to look into getting Fastpasses for the following:
1. Splash Mountain
2. Space Mountain
3. Thunder Mountain
4. Journey of the Little Mermaid
5. Peter Pan's Flight
When done right, Magic Kingdom is the most enjoyable park on property, IMO. Follow (roughly) what's outlined above and you should have no problem seeing the attractions you want to see while still moving at a leisurely pace throughout your day. Overall, have a magical time!