This doesn’t make any sense. Did you pay the full amount plus $100? Did you point out to the excursion desk that you were entitled to $50 per person off the cost? By chance did you book the excursion for the 3rd and 4th passenger in the cabin? We really need more information to give you a good answer.
That is pushing it because you have to clear agriculture inspection prior to checking in and then you have to clear security. precheck doesn't help with either of those two and those lines can be huge. If you are going to try it make sure to get a porter who will push you to the front of the lines.
Let's take a step back because a passport or a passport card is just as good as REAL ID, so what you mean to say is without a passport, a passport card or a real id you don't fly, and that is going to be the law pretty soon.
We have flown out of TPA three times after cruises and never had an issue with being able to make a flight at that time. There is one thing to be aware of when cruising out of Tampa. Sometimes there is fog that delays docking for hours and even a late afternoon flight might be too early if that happens.
By the time you get from MCO to Miami you may not save any money over simply flying into MIA. Have you looked at changing the airport you are flying out of?
I have always been able to get restaurant reservations for the popular restaurants any time during the week. Maybe that's only true for parties of two but we have never had an issue getting seated.