I have been working with them since day one 13 yrs ago. I did not build anything prior to their approval. We did however put in a milking room, milk house and now cheese processing facility with very little expense. We have been able to do all the building, wiring, plumbing ourselves. Much of our equipment, with the exception of the vat, we had or scavenged.
As for the Pasteurizer it is manly a cheese vat for me at least. I plan on making mostly raw cheeses.
I also second the idea that you contact the Dept of Agri first. There is alot you might not have even thought of.
Good luck.