My father is a certified contractor in NJ—he’s built one home, flipped four, and consistently handles upgrades and maintenance for me and his other clients.I’d appreciate any tips or stories from those who’ve turned equity into a profitable venture.

Drive around the neighborhoods to understand the lay of the land - if you have someone who will take you around and explain, better yet. 

Is the backup to use it as an STR during these months?

I don't recommend throwing the baby out with the bath water, and definitely make sure you understand the nature of the Mentor you choose.BP is a great resource to meet some amazing people. 

The Cash on Cash return?

However, they are merging with another company next month which does NOT have MLS-only memberships.

We are in a safe community, so tenants can choose to leave the door unlocked or hide a key under the mat.

I live in Seaford, NY and have been searching for areas outside of LI to do my next deal.

The better.

I know many people who own real estate that are not citizens of the US.