If you have the funds to buy Ti then do. The weight off of the valve train is helpful and the added strength is a plus as well.

The valve spring mic is the way to go, just set the valve up and do the math, add shims as needed.

That depends on the spring pack. I don't like to use Ti with flat dampers. The flat dampers tend to cut into the retainers. You may want to look into Isky tool steel retainers. They are much more durable than Ti, and almost as light.