Great stuff here,
I think can add a hand full I didn't notice reading through.
Holly is also a symbol of life and death to some. I would figure this is related to it being poisonous and medicinal.
Musselwood has the expected strength, protection, and permanence. It has been said to be used to control the will of others particularly animals. Most likely because it was used to make good ox yokes, or maybe vise versa. But, I have also been told protection from fire which I would like to learn more about if anyone has heard the same.
I will also add for earlier questions, There are a lot of trees known as Ironwood this is one it is also known as American Hornbeam and the technical folk call it Carpinus caroliniana.
Hickory twists have been handy to folk in things relating to secretes. Keeping them and fining them out. I've always heard this and encountered it all up and down the east coast of the U.S. Why make good sense to me but, I wonder if it's origins are native or pioneer, and if it pops up anywhere else.
Birch has been used for things relating to spirits. I was told as a kid that a spirit may use the shade of a birch as a doorway to the living world, or to be seen or heard by the living. It have seen where it was used relating to animation and sentience. The closest folk lore I found so far was from around Russia.
Lilac I learned growing up held the magic of rebirth. I always thought this must have to do with spring and the cloud of fragrance. One year a hard winter took some branches down off my lilac. They were tossed in the wood pile to dry till after midsummer. Then looking for a pole to prop a net for my strawberry one was cut into a stake and driven into the ground. Before the first frost it had leaves and a few flowers. I get it now.