questions about building defenses

[Tamasin]

i want to build plank and tree walls around my base.

in some sections, i will have plank walls around most of it but one side will be walled with just trees. how does a wall of trees that's 1 tree thick compare to a plank wall? which one would a raider choose to break through?

how much better are plank walls than stone walls?

if i build a stone wall outside of my plank wall, will damage to the stone wall splash onto my plank wall?

how much hammer and nail is recommended to plane boards for my walls effectively? i have 69 but i still seem to be wasting a lot of boards.

also, two claimed leantos have recently appeared outside my base. does this mean that they are planning to rob me? or why would people put leantos there? actually i found a scent at the edge of my base, which i think is from someone stealing my friend's canoe. i tracked the scent and it lead to one of the leantos. but i didnt get any evidence from the scent and no matter how many times i tried to accumulate from the scent i would just move to the spot and nothing would happen. what should i do?