I manage around 400 rentals with 14 years of experience and have never been sued once.

I am in the middle of writing my own experiences.

Our third partner, who has experience with smaller projects in Detroit, also finds this endeavor overwhelming.

Does anyone have any experience with his company and is willing to share their thoughts?

You don't need to know everything to get started; you need a foundation to build on, and the rest will come through experience and then refining your education.You can build a basic understanding of investing in 3-6 months.

I wanted to ask advice of some of you who have a lot of experience in long-term rentals. 

If I may, in your experience, is this difficult to accomplish with a HELOC already established?

From my experience working with over 400 investors, those who start with house hacking scale much faster.Good luck!

Also, our team has a lot of experience in working with Sec 8 residents and getting properties approved.

Definitely continue seeking advice from experience realtors and understand your rental market, and make sure you understand the risks involved.