Agree they could truck stuff over to the third gate, but I sure hope they get permission to put in a service tunnel underneath Harbor.
Parade Building for 3rd park . . . why not incorporate it into any berm, that may be constructed around the perimeter of said park, a parade building? I.e. cement terraces covered with dirt, then planted with trees/shrubbery, and have a parade building hidden in it.
They could even go split level, have a combined ride/show building with the parade floats on ground level, naturally, and then put the ride above it. RSR would have had room for a lot more dark ride scenes if they put the parade building below a massive showbuilding.