Yes, that young clump sprouting down low below the larger limbs above it tells me that the top of that tree is in decline.
It looks like Yellow Birch to me. Careful about rot in the trunk. Birches have a tendency to rot, and any type of tree is likely to have soft spots when it gets that large.
As others have said. If that's of the birch family those dead limbs can be extremely dangerous. Birch rots from the inside out. What looks like a fairly stable dead branch might be nothing but what I call "toilet paper" inside.
Agreed. Looks like a widow maker for sure. Definitely have a spotter and a hard hat. Your business partner senior stubby should be a good spotter.
Black Birch is a fairly common tree here in the northwoods, I don't know if you have it out there. To me it does look like yellow birch.. hard to tell by the pics, I'd say the bark is to light up top to be cherry.