There's a Facebook group, Riverwards L+I Coalition, where all your questions have already been answered.

The big ones for me: Make sure their insurance includes insuring your building. Text or email making it known that they need permission before walking on your roof. Get a Nest camera and spend the $12/mo for 60 days of footage access. Don't be afraid to talk to the developers and the construction team - talk about how you want to make sure both parties are protected, and make it clear that you're available to talk to if they need anything. Point the camera out and tell them it's there for the protection of the neighborhood - they'll appreciate it because without fail, someone's going to try to break in and steal their tools one night. You can keep track of permits on https://atlas.phila.gov/

And like everyone said - photographs! Take photos of where your walls meet your ceilings, of the new construction as it goes up, especially where it connects with your house.

Good luck! Hopefully they don't have to do any underpinning!