Those correspondences are great GD thanks.

My favourite tree is the Rowan, and according to your list there it turns out it is also the wood that corresponds to my star sign.
I would always use wood for making a wand. Somehow for me it just feels like the right material for it.
You could decorate it as much or as little as you want, but I would put one or two symbols of some kind on it to represent you. If you can do that it will make it more personal, and it will help it connect with you and you connect with it. If you are connected you will work better together.
It is intended to channel and focus your energy, so the closer you feel to each other the better the channeling and focus will be.
I like the idea of a Crystal on the end, but these are only really intended to bring the energy to a sharp point as it leaves the wand. If you don't want a particularly fine aim then crystals aren't necessary.
Blessing, consecrating and dedicating a wand help it work more closely with you aswell, so you should remember to do that too once the wand is finished.