Awsome design and I plan on making one of these soon. My only issue with what you plan on buying is that fact that the shanks are 5 1/8 inches when you want 4 inches of space. I think you are gonna need either more space or go with the 3 inch shanks. As far as how far the faucest stick out...
Im no expert but have used dry yeast a bunch of times. I would say give it a few days and wait for the bubbles to start going. It might take a little longer but be patient and if all else fails pitch some more yeast. Once again im no expert
Happy brewing and welcome to your financial...