Treats should be no more than 10% of their intake. How to figure that? I'm not sure my method is very scientific, but it works for me. I have four birds, and for BOSS, I sprinkle about 3 tablespoons of BOSS on the ground. For squash, I cut one small squash in half and put both halves in the run. I basically figure no more than 2-3 tablespoons of treat per bird per day. I don't give them any corn; if I get some, I'll knock that down to 1 TBS, since it is really just candy for them.
I've just started with fodder. I don't have any special sprouting trays. I used small margarine containers and about 1/2 teaspoon of alfalfa seed. When the sprouts were about two inches tall, I gave them both containers. Since they love to scratch up grass and weeds, I thought that would be a good amount. I didn't find any left when I looked an hour later.
My next fodder project is chia. I got a 5 lb bag of chia seeds at Costco. Should last a looooong time. We'll see how they like it. I put about a tablespoon of dirt in the bottom of the containers so the chia can grow a little taller.