[Rhinestone Cowboy]

I'm sure the more experienced folk around here will correct me if I'm wrong but I'll take a stab at answering your questions.

1- If by Racial Traits you mean Racial Technology like Psycjic Weapons, then as far as I know, no one else can use that technology. (You have to be Psychic in order to use a Psychic weapon, you have to be religious in order to use a religious artifact). Can't Give'em, Can't trade'em, can't steal'em.
If this isn't what you mean, then please explain.

2-You are correct. Once launched there is no way to recover. Even if launched by accident, once you move them from the left to the right, you can't put'em back.

3- I don't believe you can split production between yards on the same Item. If the item you are building can be split among ships, but need to be in the same spot to function (ringworld?)then you can build multiple ships at different locations. The ways you mentioned as well as a happy population and a good Racial Engineering trait will all help you build faster. I believe there is a way to check which of your yards builds at the fastest rate but I can't remember what it is!

Hope that Helps,
RhineStone Cowboy