Our county is studying building something like that.
First they did, get a consultant, that knows the details necessary for human and horse flow, building specs and all that.
Those consultants give you all kinds of ideas and tips and then you will have so much more to go by.
With such a large project, that consultant fee is peanuts, do check into that.
I know our county has checked with Priefert and ABI.
I know whole such centers both have consulted on for equestrian facilities and did an excellent job.
Both companies work with consultants and/or provide them.
There is so much in those plans that could be improved on, like keeping the right distance between buildings so firetrucks and other can attend to any disasters, size of clear span inside of buildings needed only for arenas, which would save you considerably for other and so much more.
You are starting on the road to learning so much about this and you know, that will be a wonderful road, there is so much to learn.
Start a file just for that, to keep adding all kinds of ideas and you will end up with a wonderful set up that will run so well, you will be proud of it all.
The most important part of all this is going to be where you are right now, the planing phase.
You can make mistakes in your plans, catch them and improve on what is already good.
Take all the time it takes planning and pick brains, as you are doing here and good luck with it all.