This sounds great! I might do sauteed peppers/onions and lettuce to do a taco salad if you have people watching their carbs.
Also, I would do mexican grilled corn. YUM.
I like idea of big batch sangria, if you have a drink dispenser or a punch bowl and beer. Another big batch drink I love and that goes great with tacos is summer beer. It sounds gross, but it is SO GOOD.
Sounds fine to me. I'd probably skip the pork and just do chicken and beef. If you have gfs nearby they have some frozen taco meat that is really good and reasonably priced.