Do not feel bad about piling and burning those you cut from the pasture. You probably didn't lose a single bow stave at all. ERC makes excellent bows, and it IS the same stuff you fight in your pasture. However, you need to look for ERCs that are growing either in a dense thicket or very tight up against another structure, be it a tree or wall or post or some such thing. This will prevent the limbs growing in that spot and will (hopefully) provide you a decently clear length to work with.
For diamater, it's best if they are at least 4-6 inches. ERC is relativly tension weak and will likely need a backing anyway, but the flatter you can get the back, the better. Trapping the belly a little bit will help some too. And it's OK if there is some natural deflex or string follow. It probably won't take much set and shoots very hard for its draw weight because it is so light in physical weight.
I like to start working on it before it's compleatly dry. Seems to help it bend without blowing up as hard. The stuff really lets you know when it doesn't like what you are doing.
In other words, pretty much what Blackhawk said. I haven't done the kerf cutting, but I'm sure that would help. I just quarted them and sealed the ends.
I have actually chased a ring on ERC. This is a nightmare because they tend to be very thing, but it can be done. I had a stave that I wanted to remove a lot of sapwood since I can get plain white wood any old place, and I wanted to have a lot of the pretty red heartwood left when I hit the weight I wanted. So I took off about half the sapwood. It worked really well, but again... It's a bear chasing that ring.