I'll take the first, thank you very much. Now, why would I want a timid, nervous, scared young horse as my training baby?
Simple. Once I gain the trust of the timid baby, he/she will trust me with everything. I will obtain the respect instantly of "alpha mare who protects us from the monsters". Each thing I ask may get a scared response, but eventually, I'll get a try.
And the opposite? Brave Courage Horse will test me long before they'll trust me. I'll always have to be on my toes, as they'll be testing gates, trying to run me over in-hand, and always looking to be stronger/badder/bigger than me.
A timid horse is going to be too afraid of you to crowd your space. A brave horse will run you flat over, as if you're an obstacle in the path of what he's trying to get away from.
My proof? Harley. When he got scared at the show, he'd take two or three steps towards me, then look and blow at the scary object. He didn't try to run away from me, he carefully tip toed up to me. When Mo has been afraid of something, he'll try to run me over to get away from it. Mo fights learning new things, Harley will try now that he trusts me. I never thought I'd be "alpha mare the great protector", but judging how Harley has carefully buddied up to me when he's scared of something, proves he trusts me. He didn't trust me to start. Remember when he first came here? Couldn't catch him, even with a cookie in my hands. Now, he walks up to me in the pasture, no matter how hard the wind is howling. He *trusts* me to keep him out of danger.