Starting A Dog Walking Business - What Do I Legally Need To Have, And What Is Optional?

I’m preparing to branch out of my current situation and start a dog walking/hiking business near my home. It would be just me with no other colleagues or employees. As I research and prepare, can y’all help me with what is legally necessary and what is optional but suggested Also, the location is MA in the US. Thank you so much in advance!!

(1) Do I need a business license (2) Do I need business insurance (3) Do I need to register my business with the state? (4) Do I legally NEED this permit? https://www.mass.gov/how-to/apply-for-a-commercial-dog-walking-permit (5) When I have clients fill out and sign the Service Agreement can they do this via a Google Form or do I * need * a web service like Docusign?

Thank you again!!