tree house build and lag screw strength

like_A_pike said
What species is the leaner? Any large branch scars or any other source of heart rot? How far down is the water?
How often do you get ice or sticky snow?

Not a clue what species it is

I did have an arbolist look at it a few years ago and he noted that even though its leaning, it is still a healthy tree

No idea how deep the groundwater is

We get icy and sticky snow 3 -6 months out of the year

However, it has been brought to my attention that i want to build this in the side or backyard, so im back to looking for the right tree